Question

Use the substitution method to determine the solution of the system of equations. y = -5x and 21x - 7y = 28

Answer 1

x = 1/2 y = -5/2

Explanation:

Since we already know an equation for y, we just need to plug it into the other equation.

21x - 7(-5x) = 28

21x + 35x = 28

56x = 28

x = 1/2

Now that we know x, we substitute it into the other equation, to find y.

y = -5x

y = -5(1/2)

= -5/2