Okay to find the unit rate you must find how much one bucket of paint costs so you divide 70.50/5 and then you will get 14.1 have a nice day (:
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Method 1
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Since the numerators are the same, the smaller the denominators, the greater the fraction is.
Arranging from the least to the greatest

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Method 2
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Lets change all to the same denominators



Now that all the denominators are the same, we can arrange the fractions by comparing the numerators. The bigger the numerators, the greater the fraction.
Arranging from the least to the greatest
I will assume that 0.62 is an exponent then
amount left after t seconds = f(6) = 5 - 0.82(6)^0.62
= 2.51 gallons to nearest hundredth.