If the sum of a number and nine is doubled, the result is eight less than the number. find the number.

Equation

Let the number = x

2*(x + 9) = x - 8    

Solve

2(x + 9) = x - 8                    Remove the brackets on the left

2x + 18 = x - 8                    Subtract x from both sides

2x - x + 18 = - 8                  2x and - x will combine

x + 18 = - 8                          Subtract 18 from both sides

x = -8 - 18

x = - 26

Check

LHS

2(-26 + 9)

2(-17)

-34

RHS

x - 8

-26 - 8

- 34 and the RHS = LHS and they check

75

step-by-step explanation:

question 1 is 8, question 2 is 9, question 3 is 24

step-by-step explanation:

now, the numbers they give you at the top are the key. from there, you just have to plug and chug! let's try 1, 2, and 3!

key: a=3, b=5, c=6

1. a+5

remember, a=3, so we plug that in to get 3+5=8

2. 15-c

c=6, so we plug that in to get 15-6=9

3. 4b

b=6, so we plug it in to get 4*6=24

time to try the rest on your own! if you put the answers below in a comment, i'll check them for you!