Marc and his brother start saving money at the same time. Marc starts with $145 and adds $10 every month. Ty starts with $20 and adds $15 every month. When will they have the same amount?
Let n be the number of months when they will have the same amount
So we have
145 + 10n = 20 + 15n subtract 10n , 20 from both sides
125 = 5n divide both sides by 5
25 = n
They will have the same amount after 25 months