Simplify the expression by combining like terms. then, classify the simplified expression by degree and number of terms. p4 − 5p + 2p(p3 + 5)

The answer is 4 + 17p, first distribute 2p(p3+5) which the result is 2p times 6p plus 10p and you end up p4 - 5p + 2p(6p) + 10. Then you combine like terms and you end up p4 -5p + 12p + 10p, and repeat the move (combine like terms) and you end up  with p4 + 17p. Then again you combine like terms and you end up 4 + 17p. If your wondering what happened to the p well the p is exactly like multiplying anything by 1. 

Assuming everyone in the family showers only once a day,time taken by 1 person to shower = 11*60+15= 675 secondstime taken by 5 people = 5*675 = 3,375 stime taken by the family in a week = 7*3,375 =23,625 samount of water used in a week = 23,625/(10*60) = 39.375 = 40 liters