Question 412295
I am assuming you made an error, the amount should be $550.00, not $55.00

(x)(.04)  + (15000 - x)(.03)  = 550

.04x  +   450    - .03x  = 550

.01x  = 100

x = 10000

10000(.04) = 400
5000(.03) = 150

check 400 + 150 = 550.