Solve systems, substitution x+4y=-1and y=4x-13?

Question

Please help.

Answer 1

Given equation x+4y = -1 ---------> (1)

y = 4x-13

Subtract 4x from each side.

y-4x = 4x-4x-13

y-4x = -13

Divide to each side by negitive 4.

-4y+16x = 52

16x-4y = 52 ---------> (2)

To eliminate the y value , add the equations (1) and (2).

    x+4y = -1

16x-4y = 52

____________

17x = 51

Divide to each side by17.

17x/17 = 51/17

⇒ x = 3

Substitute the x value in (1).

3+4y = -1

Subtract 3 from each side.

-3+3+4y = -1-3

4y = -4

Divide to each side by 4.

4y/4 = -4/4

⇒ y = -1

Solution x = 3, y = -1.

Answer 2

Substitution method

x+4y = -1 -------> (1)

y = 4x-13 -------> (2)

From (2) substitute the y in (1).

x+4(4x-13) = -1

x+16x-52 = -1

17x-52 = -1

Add 52 to each side.

17x-52+52 = -1+52

17x = 51

Divide to each side by 17.

17x/17 = 51/17

x = 3

substitute the x value in (1).

3+4y = -1

Subtract 3 from each side.

3-3+4y = -1-3

4y = -4

Divide to each side by 4.

4y/4 = -4/4

y =-1