Question

I think of a number, double it, and subtract two. I get nine.

Answer 1

Answer:

$2(x) - 2 = 9 \\ 2x - 2 = 9 \\ 2x = 9 + 2 \\ 2x = 11 \\ x = \frac{11}{2} \\ x = 5 \frac{1}{2}$

Answer 2

Answer:

a) 2x - 2 = 9

b) x = 5.5

Step-by-step explanation:

I think of a number

→ Lets call that number "x"

double it

→ 2x

and subtract two

→ 2x - 2

I get nine

→ 2x - 2 = 9

In an equation our aim is to make "x" the subject and solve it to find the value of x. But we must also remember that if we do something to one side then it will happen to the other side as well. If we took away 2 from x we would have to do it to the 9 as well so

2x - 2 = 9

→ Subtract 2 from both sides to isolate 2x

2x = 11

→ Divide both sides by 2 to isolate x

x = 5.5