How do you define a variable and write an expression for each phrase: the number of gallons in 21 quarts?

1 Answer
Jul 22, 2017

5 1/4 gallons

Explanation:

The way to remember this relationship is to make a mental link between the word 'quart' and the word 'quarter'.

A quarter is 1/4 and there are 4 quarts in 1 gallon.

One way to do the conversion is to consider it as a ratio. So we can write:

Let the unknown count of gallons be x

("count of gallons")/("count of quarts")->1/4=x/21

Multiply both sides by color(red)(21)

color(green)(1/4=x xx1/21" "->" "1/4color(red)(xx21)=x xx1/21color(red)(xx21))

" "color(green)((1color(red)(xx21))/4=x xx(color(red)(21))/21)

But 21/21=1

" " 21/4 = x xx1

x=5 1/4 gallons