The number of gigabytes of data Josiah can use while staying within his budget is 2.2 gigabytes.
The total amount of money that can be spent on the cell phone plan is the sum of the flat cost and the variable cost.
Total cost = flat cost + variable cost
The flat cost is the cost that remains constant each month. The variable cost is the cost that increases by gigabyte used.
$43.60 = $37 + $3x
In order to determine the value of x, combine similar terms together
$43.60 - $37 = $3x
6.6 = $3x
Divide both sides by 3
6.6/3 = x
x = 2.2 gigabytes
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