Math help please!! will give brainliest

Donald has x twenty-dollar bills and 11 ten-dollar bill. how much money does donald have? write your answer as an expression.

Renee hiked for 6 3/4 miles. after resting, renee hiked back along the same route for 5 1/4 miles. how many more miles does renee need to hike to return to the place where she started? represent your answer as a simplified mixed number, if necessary.

Among the most famous of all meteor showers are the perseids, which occur each year in early august. in some areas the frequency of visible perseids can be as high as 40 per hour. given that such sightings are poisson events, calculate the probability that an observer who has just seen a meteor will have to wait at least five minutes before seeing another.