we have the system
y=2+7x --------> equation 1
-2x+6y=172 -----> equation 2
Solve the system by elimination method
step 1
Multiply by -6 equation 1 on both sides
-6[y=2+7x ] -----> -6y=-12-42x -------> equation 3
step 2
Adds equation 2 and equation 3
-2x+6y=172
-6y=-12-42x
-------------------
-2x=172-12-42x
solve for x
42x-2x=172-12
40x=160
x=4
Find out the value of y
y=2+7x ------> y=2+7(4)=30
therefore
The solution is
x=4, y=30