Answer:
$149.50
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