Answer
He invested 1500 dollars at 3% interest.
He invested 2250 dollars at 5% interest.
Work Step by Step
Let X represent the amount of money invested at 3% interest.
After a year, he received 3% of the X amount invested as interest.
He received 3% $\times$ X = 0.03X
Also, he invested 750 more than X, or X + 750 at 5% interest.
After a year, he received 5% of the X + 750 as interest.
He received 5% $\times$ (X + 750) = 0.05X + 37.50
His total yearly interest was 157.50.
So: 0.03X + 0.05X + 37.50 = 157.50
0.08X = 120
Divide both sides by 0.08
X = 1500
He invested 1500 dollars at 3% interest.
He invested 750 more than X, or 1500 dollars, at 5% interest.
So, he invested 2250 dollars at 5% interest.
