"The product" means you're multiplying the two numbers.
"a number" refers to a variable.
"increased" means you're adding.
2x + 7 = -36
Let’s make an equation
Let’s say x = amount of years after
Smith = 8, mother = 42
3(8 + x) = 42 + x
24 + 3x = 42 + x
2x = 18, x = 9
Solution: after 9 years
What you do here is subtract g from f: x^2 - 5x + 8 - (x^2 -4); x^2 - 5x + 8 - x^2 + 4; Rearranging gives you x^2 - x^2 - 5x + 8 + 4 which is, simplified, -5x + 12