Answer:
5 weeks
Step-by-step explanation:
In order to solve for the amount of time it would take for both you and your brother to reach the same amount in savings, you need to set up an expression for each person. You save $15 a week plus you start with $75, so:
You: 15x + 75
Your brother only saves $6 a week, but starts with $120, so:
Brother: 6x + 120
If 'x' is the number of weeks in both equations, we can set the expressions equal to each other to find out how many weeks until both of your accounts are equal:
15x + 75 = 6x + 120
Subtract '6x' from both sides: 15x - 6x + 75 = 6x + 120 - 6x or 9x + 75 = 120
Subtract '75' from both sides: 9x + 75 - 75 = 120 - 75 or 9x = 45
Divide and solve for x: 9x/9 = 45/9 or x = 5 weeks
