SOLUTION: 3/5 of the number of pens displayed at the bookstore were red and the rest were blue.After 260 red pens, and 1/4 of the blue pens were sold, 1/2 of the pens were left.How many pens

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Question 1141187: 3/5 of the number of pens displayed at the bookstore were red and the rest were blue.After 260 red pens, and 1/4 of the blue pens were sold, 1/2 of the pens were left.How many pens were displayed at the bookstore first?
Can you please help me how to solve this by equation??
Thanks in advance
Found 3 solutions by josgarithmetic, rothauserc, ankor@dixie-net.com:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
p, total number of pens at the start
             RED          BLUE

Initial    3p%2F5          2p%2F5

Final      3p%2F5-260     2p%2F5-%281%2F4%29%282p%2F5%29

Total    3p%2F5-260%2B%282p%2F5-%281%2F4%29%282p%2F5%29%29=p%2F2

Solve the TOTAL equation for p.
highlight%28p=650%29

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
let x be the number of pens displayed at the bookstore first
:
3x/5 are red, 2x/5 are blue
:
260 + (2x/5)/4 = x/2
:
260 + (2x/20) = x/2
:
5200 +2x = 20x/2
:
10400 +4x = 20x
:
16x = 10400
:
x = 650
:
*************************************************
there were 650 pens at first
:
check the answer
:
there are 390 red at first and 260 blue at first
:
260 + (260/4) = (650/2)
:
260 + 65 = 325
:
325 = 325
:
answer checks
**************************************************
:

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
3/5 of the number of pens displayed at the bookstore were red and the rest were blue.
let p = total no. of pens
then
3%2F5p = no. of red pens
and
2%2F5p = no. of blue
:
After 260 red pens, and 1/4 of the blue pens were sold, 1/2 of the pens were left.
260 + 1%2F4*2%2F5p = 1%2F2p
260 + 2%2F20 = 1%2F2p
reduce fraction
260 + 1%2F10p = 1%2F2p
get rid of denominator, multiply by 10
2600 + p = 5p
2600 = 5p - p
2600 = 4p
p = 2600/4
p = 650
:
How many pens were displayed at the bookstore first? 650