Find the solution of this system of equations. x-8y=21 and 3x-8y=15

x = - 3, y = - 3

Step-by-step explanation:

Solve the following system:

{x - 8 y = 21 | (equation 1)

3 x - 8 y = 15 | (equation 2)

Swap equation 1 with equation 2:

{3 x - 8 y = 15 | (equation 1)

x - 8 y = 21 | (equation 2)

Subtract 1/3 * (equation 1) from equation 2:

{3 x - 8 y = 15 | (equation 1)

0 x - (16 y) / 3 = 16 | (equation 2)

Multiply equation 2 by 3/16:

{3 x - 8 y = 15 | (equation 1)

0 x - y = 3 | (equation 2)

Multiply equation 2 by - 1:

{3 x - 8 y = 15 | (equation 1)

0 x+y = - 3 | (equation 2)

Add 8 * (equation 2) to equation 1:

{3 x+0 y = - 9 | (equation 1)

0 x+y = - 3 | (equation 2)

Divide equation 1 by 3:

{x+0 y = - 3 | (equation 1)

0 x+y = - 3 | (equation 2)

Collect results:

Answer: {x = - 3, y = - 3