I’m not sure on what to do for these problems…can someone help me please

12 is 33 1/3% of 36 what is the whole

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

Travis and paula went to lunch. travis ordered a sandwich for $7.50 and paula ordered a burger for $5.25.after lunch, they left a 15% tip for the waiter. how many money did they spend altogether?