Question

Y = 7x + 20
4x - y = -11
solve by substitution

Answer 1

x = - 3, y = - 1

Step-by-step explanation:

y = 7x + 20 -----> equation 1

4x - y = - 11

4x - ( 7x + 20 ) = - 11

4x - 7x - 20 = - 11

- 3x = - 11 + 20

- 3x = 9

x = 9 / - 3

x = - 3

Substitute x = - 3 in equation 1,

y = 7 ( - 3 ) + 20

= - 21 + 20

y = - 1

Hence,

x = - 3

y = - 1

Answer 2

• x = -3

• y = -1

Step-by-step explanation:

y = 7x + 20 __ equation 1

4x - y = -11

y = 11 + 4x __ equation 2

using substitution method,

11 + 4x = 7x + 20

4x - 7x = 20 - 11

-3x = 9

x = -3

Find y,

y = 7x + 20

y = 7(-3) + 20

y = -1