Rachel drove 200 miles using 9 gallons of gas. At this rate, how many gallons of gas would she need to drive 420 miles?

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Answer 1 · 2016-12-09T21:35:32

Rachel would need 18.9 gallons to drive 420 miles at the same rate of consumption.

We can state the problem as a ratio:

#9# gallons #: 200# miles is the same as #x# gallons #: 420# miles

Write this as an equation gives:

#(9 gallons)/(200 mil es) = (x)/(420 mil es)#

We can now solve for #x#:

#(420 mil es) * (9 gallons)/(200 mil es) = (420 mil es) * (x)/(420 mil es)#

#(420 cancel(mil es)) * (9 gallons)/(200 cancel(mil es)) = (cancel(420) cancel(mil es)) * (x)/(cancel(420) cancel(mil es))#

#420 * (9 gallons)/200 = x#

#x = (3780 gallons)/200#

#x = 18.9 gallons#