If the sum of a number and ninenine is doubleddoubled , the result is oneone less thannbsp the number. find the number

"the sum of a number and eight is doubled, the result is one less than the number"

(x + 8) * 2 = - 1 + x

Rewrite:

(x+8) * 2 = x-1

2x + 16 = x-1 (distribute the 2)

x + 16 = - 1 (subtract x from both sides)

x = - 17 (subtract 16 from both sides)

Checking (very important):

Is (-17+8) * 2 = - 17-1?

-18 = - 18? yes.