Question

Laura borrowed a total of $18,000 from two different ba to start a business. One bank charged the equivalent of 6% simple interest, and the other charged 7.5% interest. If the total interest after 2 years was$2220, determine the amount borrowed from each bank.

Equations and inequalities
Laura borrowed a total of $18,000 from two different ba to start a business. One bank charged the equivalent of 6% simple interest, and the other charged 7.5% interest. If the total interest after 2 years was$2220, determine the amount borrowed from each bank.

2021-02-26
Let x be the amount invested at 6% so that 18000-x is the amount invested at 7.5% both in dollars.
The total interest in 2 years is \$2220 so we can write: 0.06x(2)+0.0075(18000-x)(2)=2220
Solve for x:
0.12x+2700-0.15x=2220
-0.03x+2700=2220
-0.03x=-480
$$\displaystyle{x}=-\frac{{480}}{{-{{0.03}}}}$$
x=16000
So, the amounts borrowed are:
Bank at $$\displaystyle{6}\%\to\{16000}$$
Bank at $$\displaystyle{7.5}\%\to{2000}$$
2021-08-10

Explanation on video