How would you solve x + 3y = 18 - 3x - 12y = - 75 showing all of the work

x = - 3, y = 7.

Step-by-step explanation:

x + 3y = 18

-3x - 12y = - 75

Multiply the first equation by 3:

3x + 9y = 54

Adding the last 2 equations to eliminate x:

-3y = - 21

y = 7.

Substitute y = 7 into the first equation:

x + 3 (7) = 18

x + 21 = 18

x = 18 - 21

x = - 3.