Question 1:
To determine if -7 + 9 = -9 + 7 is true, false, or open, you can use basic arithmetic.
-7 + 9 equals 2, and -9 + 7 also equals 2. Since both sides of the equation are equal, the statement is true.
Question 2:
To determine if 4x - 3 = 19 is true, false, or open, you need to solve the equation for x.
First, add 3 to both sides of the equation: 4x = 22.
Then, divide both sides by 4: x = 5.5.
Since x = 5.5 satisfies the equation, the statement is true.
Question 3:
To find the solution to the equation 16 = 4x - 4, you can solve for x.
First, add 4 to both sides of the equation: 20 = 4x.
Then, divide both sides by 4: x = 5.
So, x = 5 is a solution to the equation.
Question 4:
To determine the width of the model given that the length of the classroom is 2.4 times its width and the length of the model is 42 in, you need to set up an equation.
Let's say the width of the classroom is w.
Then, the length of the classroom is 2.4w.
Since the length of the model is 42 in, you can set up the equation: 2.4w = 42.
To solve for w, divide both sides of the equation by 2.4: w = 42/2.4 = 17.5 in.
Question 5:
To use mental math to determine the solution to x/3 = 24, you can multiply both sides of the equation by 3 to eliminate the denominator.
This gives you x = 3 * 24 = 72.
So, x = 72 is the solution.