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Dr Malcolm had some syringes on his lab. He used 25% of the syringes in the morning and another 45 syringes in the afternoon. He used the remaining 1/3 of the syringes at night. How many syringes did Dr Malcolm have at first?

 Aug 6, 2021
edited by Foaltohors  Aug 6, 2021
 #1
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If the number of remaining syringes used at night was 1/3 of the number that Dr. Malcolm started with, then the total of the number used during the morning and afternoon was 2/3 of the total.

 

Let s be the total number of syringes that Dr. Malcolm started with.

 

Then:

 

number of syringes used in the morning = 0.25s = s/4

number of syringes used ion the afternoon = 45

 

And:

 

s/4 + 45 = 2s/3

 

Multiply both sides by 12:

 

3s + 540 = 8s

5s = 540

s = 108

 

Dr. Malcolm started with 108 syringes.

 Aug 6, 2021
 #2
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25 %  is the same as   25/100 = 1/4 th

 

1/4 x  + 45   = 1/3 x

1/12 x = 45

x =   45 * 12 = ________ syringes

 Aug 6, 2021
 #3
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*** error ***

 

 

My answer is incorrect..... 

  see   Guest answer  !

ElectricPavlov  Aug 6, 2021

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