Question

The difference of a number and 9 is the same as the sum of 3 times the number and 12

Answer 1

`x = -10.5`

Explanation:

Represent the number as x

Difference of the number and x:

`x - 9` --- (1)

Sum of 3 times the number and 12:

`3 * x + 12\\` ---- (2)

Equate 1 and 2

`x - 9 = 3 * x + 12`

`x - 9 = 3x + 12`

Collect Like Terms

`x - 3x = 9 + 12`

`-2x = 21`

Make x the subject

`x = -(21)/(2)`

`x = -10.5`