Problema Solution
katia earned $12000 last years by giving tennis lesson. she invested part at 3% simple intrest and the rest at 4% simple intrest. in one year she earned $440 in intrest. how many dollars did she invest at 3%
Answer provided by our tutors
suppose x at 3% interest and 12000-x at 4% interest
we know that total interest is 440
now
3% of x + 4% of (12000-x) = 440
0.03x + 0.04 * 12000 - 0.04 x = 440
480 -0.01x =440
40 / 0.01 = x
x= 4000
so $4000 she invest at 3% and $8000 at 4% interest