Question

Given: c(x) = 2x – 6
Find c(x) = 18

Answer 1

18

X = ---- , y = 12

c

Explanation:

Solve for x, y

X = 18

__

c

Y = 12, c ≠ 0

Consider the first equation. Subtract 2y from both sides.

cx - 2y = -6

To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

cx = 18, cx - 2y = -6

Pick one of the two equations which is more simple to solve for x by isolating x on the left hand side of the equal sign.

cx = 18

Divide both sides by c.

18

X = __

c

Substitute 18/c for x in the other equation,

c x - 2y = - 6.

18

c x ( ---- ) - 2y = - 6

c

18

Multiply c times ----

c

18 - 2y = - 24

Subtract 18 from both sides of the equation.

- 2y = - 24

Divide both sides by -2.

y = 12

The system is now solved.

18

X = ---- , y = 12

C

Answer 2

18 = 2x -6 (Subtract 18 on both sides then subtract 2)
-2x = -6 -18
-6 -18 is = -24 (you add negative numbers together)
-2x = -24 (divide both numbers by -2)

X = 12