Sam two student loans totaled $31,000. One of his loans was at 2.8% simple interest and the other at 4.5%. After one year, Sam owed $1024.40 in interest. What was the amount of each loan?

User Icon for helper helper answered
13 years ago

x = loan at 2.8%, y = loan at 4.5%

0.028x + 0.045y = 1024.40
x + y = 31000

solve these two equations together for your answer

post back if you need help

User Icon for Explain Bot Explain Bot answered
11 months ago

To find the amount of each loan, we can use a system of equations.

Let's assume the amount of the loan at 2.8% interest is x, and the amount of the loan at 4.5% interest is y.

According to the given information, the total amount of the loans is $31,000. Therefore, our first equation is:

x + y = 31,000 -- Equation (1)

Now, let's calculate the interest for each loan.

The interest on the first loan at 2.8% can be calculated using the formula: I = P * R * T, where I is the interest, P is the principal (loan amount), R is the rate, and T is the time (1 year in this case). Plugging in the values, we get:

I1 = x * 0.028 * 1 -- Equation (2)

Similarly, the interest on the second loan at 4.5% can be calculated:

I2 = y * 0.045 * 1 -- Equation (3)

Given that the total interest after one year is $1024.40, our third equation is:

I1 + I2 = 1024.40 -- Equation (4)

Now, we have a system of three equations:
x + y = 31,000 -- Equation (1)
I1 = x * 0.028 * 1 -- Equation (2)
I2 = y * 0.045 * 1 -- Equation (3)
I1 + I2 = 1024.40 -- Equation (4)

To solve this system of equations, we can substitute equations (2) and (3) into equation (4) and simplify:

x * 0.028 + y * 0.045 = 1024.40 -- Equation (5)

To eliminate the decimals, we can multiply this equation by 100:

2.8x + 4.5y = 102440 -- Equation (6)

Now, we can solve the system of equations (1) and (6) using the elimination method.

1) Multiply equation (1) by 2.8 to cancel out the x term:

2.8x + 2.8y = 86800 -- Equation (7)

2) Subtract equation (7) from equation (6) to eliminate the x term:

(2.8x + 4.5y) - (2.8x + 2.8y) = 102440 - 86800

1.7y = 15640

3) Solve for y:

y = 15640 / 1.7

y ≈ 9200

Now, substitute the value of y back into equation (1) to find x:

x + 9200 = 31000

x ≈ 21800

Therefore, Sam's loans were approximately $21,800 and $9,200.