System of Equation with substitutions

Question

A high risk stock pays dividends at a rate of 12% per year and a savings account pays 5% interest per year. How much of a $15,000 investment should be put into stock and how much in savings to obtain a return of 8% per year.

Equation 1;

Equation 2;

Substitution;

Answer 1

X+y=15000

.12x + .05y = .08*15000

X+y=15000

.12x + .05y= 1200

.12x + .05(15000-x)=1200

12x+5(15000-x)=120000

12x + 75000-5x = 120000

7x= 45000

X=6428.57

Y=8571.43