Question 914509
let x be the certain number, then
3*(x - 18) = (x + 15) - 5
3x - 54 = x + 15 - 5
subtract x from both sides of =
2x - 54 = x + 10
add 54 to both sides of =
2x = 64
divide both sides of = by 2
x = 32
the certain number is 32