To answer, let x be the amount that is invested at 8% return. With this representation, the amount for that is invested at 7% return is 5700 - x. The total return is calculated through the equation,
R = P x i x n
where R is the return, P is the principal amount, i is the interest, and n is the number of years.
Substituting the known values,
420 = (x)(0.08) + (5700 - x)(0.07)
The value of x from the equation is 2100.
The value invested at 8% is $2,100 and the value invested at 7% is $3,600.
