To find out when Miguel and Christina will have the same amount of gas in their tanks, we need to set up a comparison of how much gas each has after some weeks.
Let \( t \) represent the number of weeks.
-
Miguel's gas usage:
- Miguel starts with a full tank of 20 gallons and uses 1.5 gallons per week.
- So, after \( t \) weeks, the amount of gas Miguel has is: \[ M(t) = 20 - 1.5t \]
-
Christina's gas usage:
- Christina starts with a full tank of 16 gallons and uses 1 gallon per week.
- So, after \( t \) weeks, the amount of gas Christina has is: \[ C(t) = 16 - t \]
Now we set the two equations equal to each other in order to find the point at which they have the same amount of gas: \[ 20 - 1.5t = 16 - t \]
Now, let’s solve for \( t \):
-
Rearranging: \[ 20 - 16 = -t + 1.5t \] \[ 4 = 0.5t \]
-
Dividing both sides by 0.5: \[ t = \frac{4}{0.5} = 8 \]
Thus, Miguel and Christina will have the same amount of gas in their tanks after 8 weeks.
Therefore, the correct response is: After 8 weeks they will have the same amount of gas in their tanks.