Dr. trekcir has $875 to invest. he invests some of it in account#1 paying 8% annual interest and the rest of it in account#2 paying 4% annual interest. after 1 year total interest is $49.00. find hou much is invested in each account

Here's what the equation would look like (I'm using the variable n for the investments):
0.08n + 0.04(875-n) = 49
Multiply both sides by 100:
8n + 3500 - 4n = 4900
Simplify:
4n+3500=4900
Isolate n:
4n = 1400
n = 350
8% invested: 350
4% invested: 525