total interest=346.5=7500*.05 + x*.04

solve for x.

can you help me solve for x i got this from a word problem i had but when i get to this point lost i am.

this is the word problem:

A person invests $7,500 part at 5% and the remainder at 4% simple interest. If the total interest at the end of the first year was $346.50, find the amount invested at 4%.