Larry invested part of his 17,000 advance at 5% annual simple interest and the rest at 3% annual simple interest. if his total yearly interest from both accounts was $530, find the amount invested at easch rate.

bearing in mind that  

a = amount invested at 5%

b = amount invested at 3%

how much is 5% of "a"?  well is simply (5/100) * a, or 0.05a.

how much is 3% of "b"?  well is simply (3/100) * b or 0.03b.

we also know that "b" is the rest invested after "a" was invested, so since the total amount is 17000, then  a + b = 17000, b = 17000 - a.

and since the yield or amount of both of those interests after the same year is 530, then