Question

Given that

R
=
2
x
+
9
y

Find
x
when
y
=
3
and
R
=
13
.

Answer 1

x=-7

Explanation:

We are given the expression:

R=2x +9y

We want to find x when R=13 and y=3. Therefore, we must substitute the numbers in for the variables.

13=2x+9(3)

Multiply 9 and 3.

13=2x+27

Now we must solve for x by isolating x on one side of the equation.

27 is being added to 2x. The inverse of addition is subtraction, so subtract 27 from both sides.

13-27=2x+27-27

13-27=2x

-14=2x

x is being multiplied by 2. The inverse of multiplication is division, so divide both sides by 2.

-14/2=2x/2

-14/2=x

-7=x

x=-7

Answer 2

-7

Explanation:

To find x, substitute the values and solve.

R = 2x + 9y

It becomes:

2x + 27 = 13

Rearrange and solve

2x = -14

x = -7

Hope this helps