SOLUTION: A. Perfume is sold in 10mL and 25mL bottles. If a chemist orders 600mL of perfume and receives 33 bottles, how many of each did he receive? B. A boat travels 120km upstream agai

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Question 370033: A. Perfume is sold in 10mL and 25mL bottles. If a chemist orders 600mL of perfume and receives 33 bottles, how many of each did he receive?
B. A boat travels 120km upstream against the current in 5 hours, but makes the return trip in only four hours. Find the speed of the current and the speed of the boat in still water.
Please help, Ive tried all different ways for both questions, but I must be using the wrong information.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let A be the number of 10ml bottle, B the number of 25mL bottles.
1.A%2BB=33
.
.
10A%2B25B=600
2.2A%2B5B=120
Multiply eq. 1 by (-2) and add to eq. 2,
-2A-2B%2B2A%2B5B=-66%2B120
3B=54
highlight%28B=18%29
Then from eq. 1,
A%2B18=33
highlight%28A=15%29
.
.
.
Let B be the boat speed, C the river current.
Rate*Time=Distance.
With the current,
%28B%2BC%294=120
1.B%2BC=30
Against the current,
%28B-C%295=120
2.B-C=24
Add eq. 1 to eq. 2,
B%2BC%2BB-C=30%2B24
2B=54
highlight%28B=27%29kph
From eq. 1,
27%2BC=30
highlight%28C=3%29kph