Answer :
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
----> 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