Question

How do you solve `2r - 15= 120`?

Answer 1

`r=135/2`

Explanation:

`"isolate 2r by adding 15 to both sides of the equation"`

`2rcancel(-15)cancel(+15)=120+15`

`rArr2r=135`

`"divide both sides by 2"`

`(cancel(2) r)/cancel(2)=135/2`

`rArrr=135/2`

`color(blue)"As a check"`

Substitute this value into the left side and if equal to the right then it is the solution.

`(2xx135/2)-15=135-15=120=" right side"`

`rArrr=135/2" is the solution"`

Answer 2

`r=67.5` or `r=67 1/2`

Explanation:

Step 1) Add both sides of the equation with `15`

`2r-15=120`

`2r=120+15`

`2r=135`

Step 2) Divide both sides of the equation with `2`

`r=135/2`

`r=67 1/2` or `r=67.5`

It is preferred that you put the variable on the left side of the equation and that you simplify your answer unless stated not to

( You can write your answer as a fraction or a decimal unless stated in the question )