Let's set up equations for the amount of money Sam and Alex have after \( w \) weeks.
For Sam:
- Starts with $20 and saves $5 per week.
- After \( w \) weeks, Sam's total amount is given by: \[ S(w) = 20 + 5w \]
For Alex:
- Starts with $40 and saves $3 per week.
- After \( w \) weeks, Alex's total amount is given by: \[ A(w) = 40 + 3w \]
We want to find out when \( S(w) = A(w) \): \[ 20 + 5w = 40 + 3w \]
Now, let's solve this equation step by step.
-
Subtract \( 3w \) from both sides: \[ 20 + 5w - 3w = 40 \] \[ 20 + 2w = 40 \]
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Subtract 20 from both sides: \[ 2w = 20 \]
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Divide by 2: \[ w = 10 \]
Thus, after 10 weeks both Sam and Alex will have the same amount of money.
The answer is C. 10.