10. What is the value of x in the solution to the system of equations? x – 2y = 7
3x + 2y = 21
+/-

Solve for x in first equation:

x-2y=7

Add “2y” to both sides

x=2y+7

Put this in to second equation:

3(2y+7)+2y=21

Solve for y:

Distribute the 3 into the ()

6y+21+2y=21

Combine the like y terms

8y+21=21

Subtract 21 from both sides

8y=0

Divide by 8 on both sides

y=0

Put this into the first solved equation:

x=2(0)+7

Solve for x:

Multiple 2(0)

x=0+7

Add 0 and 7

x=7

So the value of x is positive 7.