How do I solve this % question?

Question

Cindy invested some of her $15,000 in bonds that made a 6% profit and the rest in bonds that made a 10% profit.  If the profit on the 10% bonds was $1,000 more than the profit on the 6% bonds, how much did Cindy invest in the 6% bonds?

Answer 1

Let T = amt at 1% and S = amt at 6%

T + S = Total invested = 15000

 

.01T = profit on 10% investment and .06S = profit on 6% investment

.01T = .06S + 1000

 

Multiply the first equation by 6 and the 2nd equation by 100

6T + 6S = 90000

10T -6S = 100000

 

Add

16T = 190000 => T = 11875

S = 15000 - 11875 = 3125