Question 1202459
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Using a proportion, as the other tutor did, is one good formal way for solving the problem.<br>
A slightly less formal way, given that the rate of fuel consumption is constant, is to multiply the given number of gallons of gas by the ratio of the two times:<br>
{{{15*(35/3) = (15*35)/3 = 5*35 = 175}}}<br>
ANSWER: 175 gallons<br>
And a third easy solution method is to use the given data to determine the rate of fuel consumption in gallons per hour and multiply that number by 35 hours:<br>
{{{15/3=5}}}
{{{5*35=175}}}<br>
The actual calculation in all three solution methods is the same; so the choice of which method is up to the student -- find the method that "works" for you an use it.<br>