Question

WILL BEST ANSWER
A number is decreased by seven. Then, the new number is multiplied by 3 to get an answer of -9.
What is the original number?
-30
30
4
-4
So confusing? How do I work it out?

Answer 1

So to work it out, we need to work backwords.

They said our final answer was -9. And we need to find the original number.

So we have to go backwords with the steps doing the opposite of what they had originally did to get to the first number.

Do you understand?

Answer 2

Yeah a little, how would I work it backwards?

Answer 3

So for example,

A number is multiplied by 4, and now we get 20

So to work this backwords, we have to divide 20 by 4 to know which number when multiplied by 4 got us to 20. And that is 5.

That is just an example. Does that make it more clear to you? (:

Answer 4

Yes, Thank you!

Answer 5

So, the question is:

A number is decreased by seven. Then, the new number is multiplied by 3 to get an answer of -9.

So we have to work one step at a time backwords until we reach the beginning of the question.

So what number multiplied by 3 would get us -9?

Answer 6

Thinking...

Answer 7

we would multiply by 3 on the answer choices to see which one equals -9 right? @AbdullahM

Answer 8

not in the answer choices, just divide -9 by 3 to find out what the previous number was. We're working backwords and once we finish all the steps we will get the answer which is one of the answer choices.

Answer 9

so... We divide the answer choices by -9 and then multiply by 3?

Answer 10

@AbdullahM

Answer 11

we have nothing to do with the answer choices right now.

Answer 12

So, first tell me what is \(\sf\Large \frac{-9}{3}=?\)

Answer 13

@AbdullahM -3

Answer 14

Ok, now we move back to the step before it which is:

A number is decreased by seven

Answer 15

So lets say the original number is 'n'.

Then that means

n - 7 = -3

Answer 16

4!!!!!

Answer 17

Thank you! @AbdullahM

Answer 18

Good job! :D

Answer 19

:)

Answer 20

And just ot make sure, you can use 4 and work through the steps like normal to make sure we arrive at -9

Answer 21

Thank you so much!

Answer 22

A number is decreased by seven. Then, the new number is multiplied by 3 to get an answer of -9.

So we have

4 - 7 = -3

and then

-3 x 3 = -9

So it works, and is your correct answer :)

Answer 23

Okay Thank you!