RV=D relates fuel efficiency ( a rate ) with fuel volume and distance. This is a basic uniform rates situation.
If variables are c for miles in city driving, and h for miles in highway driving then you may arrange rv=c for city driving at rate r, and Rv=h for highway driving at rate R.
DATA TABLE USING VALUES DESCRIBED AND VARIABLES STILL NEEDED
rate volume(gallons) distance (miles)
HIGHWAY 26 h/26 h
CITY 18 c/18 c
Total 22
This gives a formula for volume of fuel used if h and c are both known.
Question (b):
rate volume distance
HWY 26 h/26 h
CTY 18 90/18 90
Total 22 480
Make the obvious equations and see if they make sense together or what more the results mean.
--------the amount of highway distance possible. If you look at the sum , as if . Is it true or not?
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---------certainly this is true.
Enough fuel, yes, for the 480 mile trip which includes 90 miles in the city.