Let's solve each of these problems step by step.
- Jillian's Cookie Sales: The system of equations is: \[ \begin{align*} x + y &= 24 \quad \text{(1)} \ 3.50x + 5.00y &= 97.50 \quad \text{(2)} \end{align*} \] From equation (1), we can express \(y\): \[ y = 24 - x \] Substituting \(y\) in equation (2): \[ 3.50x + 5.00(24 - x) = 97.50 \ 3.50x + 120 - 5.00x = 97.50 \ -1.50x + 120 = 97.50 \ -1.50x = -22.50 \ x = 15 \] Therefore, the number of 10 oz. boxes sold is 15.
- Second System of Equations: The equations are: \[ \begin{align*} 2x + y &= 1 \quad \text{(1)} \ 3x - y &= -6 \quad \text{(2)} \end{align*} \] Adding both equations to eliminate \(y\): \[ (2x + y) + (3x - y) = 1 + (-6) \ 5x = -5 \ x = -1 \] Substitute \(x\) into equation (1): \[ 2(-1) + y = 1 \ -2 + y = 1 \ y = 3 \] The solution is (–1, 3).
- Mira's Numbers: The system of equations is: \[ \begin{align*} x - y &= 4 \quad \text{(1)} \ \frac{1}{2}x + \frac{1}{2}y &= 18 \quad \text{(2)} \end{align*} \] Equation (2) can be rewritten as: \[ x + y = 36 \] Now, we solve: \[ \begin{align*} x - y &= 4 \quad \text{(3)} \ x + y &= 36 \quad \text{(4)} \end{align*} \] Adding (3) and (4): \[ 2x = 40 \implies x = 20 \] Substitute \(x\) into (4): \[ 20 + y = 36 \implies y = 16 \] The two numbers Mira picked are 20 and 16.
- System A and B: The equations: \[ \begin{align*} \frac{1}{2}x + 3y &= 11 \quad \text{(1)} \ 5x - y &= 17 \quad \text{(2)} \end{align*} \] From (2), rearranging gives: \[ y = 5x - 17 \] Substitute \(y\) into (1): \[ \frac{1}{2}x + 3(5x - 17) = 11 \ \frac{1}{2}x + 15x - 51 = 11 \ 15.5x = 62 \ x = 4 \] Substitute back for \(y\): \[ y = 5(4) - 17 = 20 - 17 = 3 \] The solution is (4, 3).
- Linear Equations: The equations are: \[ \begin{align*} y - 4x &= 7 \quad \text{(1)} \ 2y + 4x &= 2 \quad \text{(2)} \end{align*} \] From (1): \[ y = 4x + 7 \] Substitute into (2): \[ 2(4x + 7) + 4x = 2 \ 8x + 14 + 4x = 2 \ 12x = -12 \ x = -1 \] Substitute back for \(y\): \[ y = 4(-1) + 7 = -4 + 7 = 3 \] The solution is (–1, 3).
- Equations with Solution \( (−2, −1) \): You are given several systems to evaluate. The first is: \[ 5x = -10 \quad (1)\ 11x - 9y = -13 \quad (2) \] Substitute the values \(x = -2\) and \(y = -1\) to check if they work: \[ 11(-2) - 9(-1) = -13 \ -22 + 9 = -13 \ Yes. \] Check others similarly: The compatible system is \( -6x + 3y = -1, ; 5x = -10\).
- Costs of Jerseys and Shorts: Using the equations: \[ \begin{align*} 12x + 12y &= 156 \quad \text{(1)} \ 4x + 6y &= 62 \quad \text{(2)} \end{align*} \] From (1): \[ x + y = 13 \implies y = 13 - x \] Substitute into (2): \[ 4x + 6(13 - x) = 62 \ 4x + 78 - 6x = 62 \ -2x + 78 = 62 \ -2x = -16 \ x = 8 \] Thus, the cost of each jersey is $8.
- System of Linear Equations: The equations are: \[ \begin{align*} y - x &= 6 \quad \text{(1)} \ y + x &= -10 \quad \text{(2)} \end{align*} \] Adding both: \[ 2y = -4 \implies y = -2 \] Substitute \(y\) into (1): \[ -2 - x = 6 \implies -x = 8 \implies x = -8. \] The solution is (−8, −2).
- Jose's Test Grades: The system is: \[ \begin{align*} x - y &= 16 \quad \text{(1)} \ \frac{1}{8}x + \frac{1}{2}y &= 52 \quad \text{(2)} \end{align*} \] Expressing \(y\): \[ y = x - 16 \] Substitute into (2): \[ \frac{1}{8}x + \frac{1}{2}(x - 16) = 52 \ \frac{1}{8}x + \frac{1}{2}x - 8 = 52 \ \frac{1}{8}x + \frac{4}{8}x = 60 \ \frac{5}{8}x = 60 \implies x = 96 \] The higher grade is 96.
- Jarred's DVDs: The equations: \[ \begin{align*} x + y &= 3500 \quad \text{(1)} \ x - y &= 2342 \quad \text{(2)} \end{align*} \] Adding both: \[ 2x = 5842 \implies x = 2921 \] Therefore, Jarred has 2,921 contemporary titles.
In summary, here are the answers to the respective questions:
- 15
- (–1, 3)
- 20 and 16
- (4, 3)
- (–1, 3)
- −6x + 3y = −1
- $8
- (−8, −2)
- 96
- 2,921