Use a sum or difference formula to find the exact value of the following. cos cos sin sin

Natasha spent 1 1/2 hours on the beach. she fell asleep for 3/4 of the time she was on the beach and then woke up with a terrible sunburn.how many hours was natasha asleep on the beach?

Pelle's sister is three years older than pelle the father is 5 times as old as pelle the mother was 28 when the sister was born altogether they are 98 years old how old is pelle?

Which system of linear inequalites is represented by the graph?