a The distance traveled is the same irrespective of the variable used.
B
b Isolate g on one side.
C
c Substitute 6 hours into one of the equations.
A
a 55t=20g
B
b g=11/4t
C
c 330 miles
Practice makes perfect
a The distance d we travel in a car is expressed by two different equations. However, the traveled distance is the same in each case. So we can equate the given equations in order to relate g and t.
This means that we need 16 and a half gallons of gasoline for our trip. Furthermore, if we want to calculate how far we can travel, we need to use one of the equations given in the original problem. Let's use the second one.
