You have $80 and your brother has $275 dollars. you save $10 of your allowance each week. your brother spends his allowance plus $15 each week.

1. write an equation to model this.

2. how long before you have as much money as your brother?

3. how much have you saved when you catch up to him?

You start with 80 and ADD 10 each week
> 80 + 10x

Your brother starts with 275 and SUBTRACTS 15 each week
---> 275 - 15x

Set expressions equal to find out when you have same amount as your brother.

80 +10x = 275 -15x

Add 15x to both sides

80 +25x = 275

Subtract 80 from both sides

25x = 195

Divide by 25

x = 7.8  (Round up to 8)

This means in 8 weeks you will have caught up and if fact have more money than your brother.

Since you save 10 per week, in 8 weeks the Total saved = 10*8 = 80