First you want to find the equation to the problem, which is 5x + 10 = 20. Then, subtract 10 from each side (the 20 and the 10) (the ten cancels out). You are then left with 5x = 10. Divide by 5 on each side (same thing; 5 cancels out and you do 10 ÷ 5) which equals x = 2.
