5x-42=y

X+Y=18

How do I find the variables numeric value

5x - 42 = y

x + y = 18

To find the variables numeric value, you can do substitution and plug in the equation of y (first equation) into the second equation because y is already by itself.

x + (5x - 42) = 18

x + 5x - 42 = 18

6x - 42 = 18

Add 42 on both sides

6x = 60

Divide 6 on both sides to get x by itself

x = 10

Now that you know "x", you can plug it into either of the equations to find "y"

x + y = 18

10 + y = 18

y = 8

5x - 42 = y

5 (10) - 42 = y

50 - 42 = y

8 = y

x = 10, y = 8