Question 439617: Debbie, an outside saleswoman, uses her car for both business and pleasure. Last year, she traveled 30,000 miles, using 900 gallons of gasoline. Her car gets 40 miles per gallon on the highway and 25 in the city. She can deduct all highway travel, but no city travel, on her taxes. How many miles should Debbie be allowed as a business expense?
I set my equation up as 40x + 25(30000 - x) = 30000(900), but this isn't right because the answer is too large. I tried also 40x + 25x = 900 but do not know how to factor in the 30,000 miles. Could you explain to me step by step how to solve this problem, and how and why the equation to be solved is set up the way that it is?
Answer by rwm(914)   (Show Source):
You can put this solution on YOUR website! We will have at least two unknowns so we need at least two equations.
one equation for each unknown
You were close.
Thanks for showing what you tried. I am more likely to help someone who tries.
I think you confused yourself by trying to combine the two equations too soon.
highway gallons + city gallons = 900
h+c=900
40h+25c=30000
highway miles + city miles=30000
h=500
c=400
deduct the 40*500 miles for business
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