8 men and 12boys can finish a house in 5 days while 6 men and 8 boys can finish in 7-days find the time taken by one man alone and that of one Boy Alone to finish the work

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.

Ablue whale traveled 3112 miles in 214hours. what was the whale's rate in yards per hour? (1 mile = 1,760 yards)

Suppose that prices of a gallon of milk at various stores in one town have a mean of $3.71 with a standard deviation of $0.10. using chebyshev's theorem, what is the minimum percentage of stores that sell a gallon of milk for between $3.41 and $4.01? round your answer to one decimal place.