The average person's head has about 100,000 strands of hair what is that in scientific notation

Umm.. just started this 2day and its not on my notes(p′︵‵。)

Solve 2x+y=3 x+y=5 in substitution method

Sarah took the advertising department from her company on a round trip to meet with a potential client. including sarah a total of 11 people took the trip. she was able to purchase coach tickets for $280 and first class tickets for $1280. she used her total budget for airfare for the trip, which was $6080. how many first class tickets did she buy? how many coach tickets did she buy?