212.5 miles because Gavin drives 85 miles on 10 gallons therefore 85/10=8.5 miles per gallon X 25 gallons=212.5
ANSWER

EXPLANATION
We can use any two points to determine the slope.
The line passes through;
(-3,1) and (-5,5).
The slope is given by

This implies that;


We can now find the equation using the formula;


Expand:


Well it would be 4 2/3 or 14/3