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

2 Answers
Jim G.
Jul 20, 2017

#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"#

Izzy H.
Jul 20, 2017

#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 )

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