On a snowy day, the amount of money Billy earns, M, varies directly with the number of
driveways that he shovels, D. When he shovels 7 driveways, he earns $80.50. How much does
he earn if he shovels 13 driveways?

$149.50

Step-by-step explanation:

M varies directly as D

M ~ D

M = KD

Where:

M = money earn

D = Driveway

K = assumed constant

Therefore

M = KD

$80.50 = k * 7

K = $80.50 / 7

K = $ 11.50

To know how much he earns if he shoves 13 drive way, we repeat the relationship.

That is:

M = KD

M = $11.50 * 13

M = $149.50

He makes $149.50 after shoving 13 driveways