Jessica earned a total of $370 in simple interest from two separate accounts. In an account earning 4% interest, Jessica invested $1,600 more than four times the amount she invested in an account earning 1%. How much did she invest in each account?

b = 4 a + 1600

Ia = 0.01 a
Ib = 0.04 b
Ia + Ib = 370 so 0.01a + 0.04 b = 370 or a + 4 b = 37,000
so
a + 4(4a+1600) = 37,000
solve for a, go back and find b