You must factor.

The factored form is equal to the assigned form.

Values a, b correspond to the factored 1, -1.
Value of x however remains unknown. But we can change that.
Given factored result,

We can set expression equal to 0 then find such x that when added with number a or b results with 0.

Hence x has 2 solutions.

Hope this helps.
Answer:
30 miles
Step-by-step explanation:
Get the x variable on one side and the numbers another side.
9/10(x + 2/3) = 4 1/2
Distribute the 9/10 across the x and 2/3.
(9/10)x + 18/30 = 4 1/2
Simplify 18/30 to make our life easier.
(9/10)x + 3/5 = 4 1/2
Subtract 3/5 from each side of the equation.
(9/10)x = 3 9/10
Divide both sides by 9/10.
x = 4 1/3