Question

Solve the following system of equations by the substitution method.

10x + 10y = 1
x = y - 3

What is the value of y?

A) -29/20
B) 31/20
C) -3/2

Answer 1

10(y-3)+y=1

20y=31

Y=31/20

Answer 2

10x + 10 y = 1 equation. 1

x = y - 3

x - y = 3 equation 2

then,

multiply 10 on equation 2

so,

10x - 10y = 30 equation 3

so ,

solve the equation 2

10x + 10y = 1

10x - 10y = 30

so,

20 y = -29

y = -29/20