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16 votes
Fifteen less than twice a number is 21.
What is the missing number? |

2 Answers

8 votes

Answer:

2y - 15

Explanation:

well 15 LESS than TWICE a number. okay so let’s start off by making a variable for the unknown number.... y. the variable is y. so now we have to think, TWICE that number, but we don’t know the number.

Now that we have the variable and we know it has to be doubled, let’s start off making the first half... we can out that into 2y. which is 2 multiplied by the unknown number.

now that we have the first half done, we have to take the 15 less. Less can mean or subtract in this kind of situation. but for this certain scenario, it will be subtraction. so the equation would be 2y - 15.

User Seif Sayed
by
3.8k points
9 votes

Hello!

First of all, let the number be r.

"twice a number" means we multiply that number by 2:

2r

Subtract 15 (fifteen less)

2r-15

This is equal to 21:

2r-15=21


\rule{160}{2}

Solve the equation:

2r=21+15

2r=36

Divide both sides by 2:

r=18

Hope everything is clear.

Let me know if you have any questions!

#LearnWithJoy


\rule{2}{2}~\bf{An~Emotional~Helper}~\rule{2}{2}}

User VlatkoB
by
3.4k points