Percent problem using linear equation

Question

12,000 in fund A returned a 3% profit. Amount in fund B returned a 10% profit. How much was invested in fund B if both funds together returned a 6% profit?

Answer 1

Fund A: profit A = (12,000)(0 .03) = 360

Fund B: profit B = 0.1x, where x is amount invested

Together: fund A & B = 12,000 + x; profit of fund A & B = (12,000 + x)(0.06)

Therefore, profit A + profit B = profit of fund A & B, which is

360 + 0.1x = (12,000+ x)((0.06)

360 + 0.1x = 720 + 0.06x

0.04x = 360

x = 9,000

Ans) Fund B invested is $9,000