SOLUTION: I add 12 to a certain number and then double the result. The answer is 42. Find the original number?

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Question 1189302: I add 12 to a certain number and then double the result. The answer is 42. Find the original number?
Found 2 solutions by ikleyn, josgarithmetic:
Answer by ikleyn(52800) About Me  (Show Source):
You can put this solution on YOUR website!
.
I add 12 to a certain number and then double the result. The answer is 42. Find the original number.
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To solve the problem, go backward: 

    Divide 42 by 2 to get 21.

    Subtract 12 from 21 to get 9,   which is your  ANSWER

Solved and explained.



Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
Directly translatable as an equation.

"A certain number, original number", n.

2%2812%2Bn%29=42-----------easily solvable.