First lets calculate how much he makes in 7 hours from his hourly pay.
Multiply 7 hours by $7, which equals $49, this is known as his base pay.
Now we subtract his base pay from what he wants to earn,
$87.50 - $49 = $38.50
He needs to earn $38.50 in tips.
He keeps 60% of his tip money, so we would divide the amount he needs ( $38.50) by 0.60 ( 60% as a decimal) to find out how much he needs in tips.
38.50 / 0.60 = 64.17
He needs to earn $64.17 in tips
