Write an equation to represent the number puzzle. Use x as the
variable. Then find the solution using guess-check-and-improve.
6 added to a number is the same as 18 subtracted from 4 times the number. What is the number?

a. 6 − x = 4x − 18, 4.8 c. 6 + x = 4x − 18, 7
b. 6 + x = 4x − 18, 9 d. 6 + x = 4x − 18, 8