Question 78939
3x+7y=18
x+2y=5


1.) solve one equation for x
x+2y=5
x=5-2y


2.) Plug in the value of x in the second equation
3x+7y=18
3(5-2y)+7y=5
15-6y+7y=5
1y=-10
y=-10


3.) Plug the value of y into either equation to solve for x
x+2y=5
x+2(-10)=5
x+(-20)=5
x-20=5
x=25


x=25
y=-10