Rick was given a 15% tip waiting on a table of customers who ordered $60.00 in food and drinks. How much did Rick earn in tips for waiting on this table?

Fa bus driver leaves her first stop by 7: 00 a.m., her route will take less than 37 minutes. if she leaves after 7: 00 a.m., she estimates that the same route will take no less than 42 minutes. which inequality represents the time it takes to drive the route, r?

Having a hard time understanding this question (see attachment).

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25