Multiply both sides of the second equation by 4. That will give you -4x in the second equation which when added to 4x of the first equation will eliminate x.
Second equation:
-x + 3y = 6
Multiply the second equation by 4 on both sides:
-4x + 12y = 26
Example
from pir^2 ro pi(2r)^2
pi(2r)^2=pi4r^2=4pir^2
basicaly we look for any no options and ones where second is 4 times first
B
pi2^2, if it is double, pi4^2
B
