math word problems
posted by kayla .
I tried doing this problem but i just don't get it:
A boy has 16 coins consisting of nickles, dimes, and quarters. The number of nickles is 3 less than the number of dimes and the value of the quarters is 55 cents greater than the value of the dimes. How many coins of each kind has he?
2) If three pipes are all opened, they can fill an empty swimming pool in 3 hours. The largest pipe alone takes one third the time that the smallest pipe takes and half the time the other pipe takes. How long will each pipe take by itself.

1)
N+D+Q=16
N=D3
.25Q.55=.10D
2)
remember Distance=rate*time? It applies here, let volume=rate*time
time= volume/rate
3hrs=volume/(Largestrate + otherrate+smallerrate)
but Largestrate=3*smallestrate
and largestrate=2*otherrate
so
3=volume/(largestrate+1/2 largestrate+1/3s largestrate)
11/6 largest rate=1/3 volume
largest rate= 2/11 volume or the largest pipe can empty the pool in 11/2 of an hour or 5.5 hrs. 
a boat weighs 1500 lb more than its motor and 1900 lb more than its trailer. Together the boat and the motor weigh five times as much as the trailer. how much does the baot weigh?