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 September 25th, 2018, 09:47 PM #1 Banned Camp   Joined: Sep 2018 From: tytyt Posts: 32 Thanks: 0 How to solve this Hello If the ratio of chocolates to ice-cream cones in a box is 5:8 and the number of chocolates is 30, find the number of ice-cream cones. Last edited by skipjack; June 25th, 2019 at 03:52 PM.
 September 25th, 2018, 10:43 PM #2 Senior Member     Joined: Sep 2015 From: USA Posts: 2,530 Thanks: 1390 what is your problem?
 September 25th, 2018, 11:12 PM #3 Banned Camp   Joined: Sep 2018 From: tytyt Posts: 32 Thanks: 0 Hello The chocolates to ice-cream cones ratio is 5:8=chocolates:ice-cream cones 5/8=30/ice-cream cones ice-cream cones = 30*8/5 ice-cream cones = 240/5 ice-cream cones will be 48; is this right/correct? Last edited by skipjack; June 25th, 2019 at 03:54 PM.
 September 26th, 2018, 06:50 AM #4 Global Moderator   Joined: Dec 2006 Posts: 20,926 Thanks: 2205 Yes.
 June 25th, 2019, 03:37 PM #5 Newbie   Joined: Jun 2019 From: New York Posts: 23 Thanks: 0 Hello I got 48 as well. By placing 5/30= 8/x, cross multiplying it will be 5x=240.Then x= 240/5, which is equal to 48. 48 Ice cream cones to 30 chocolates. I saw these 2 links, that was helpful for me in solving this problem: 1) https://mathbitsnotebook.com/Geometr...y/SMRatio.html 2) Hope this helps, I agree with you it is 48.
 June 25th, 2019, 07:12 PM #6 Senior Member   Joined: Jan 2014 From: The backwoods of Northern Ontario Posts: 391 Thanks: 70 5:8 = 30:C Here's the way I taught my elementary pupils to solve it when I was a teacher: What do you have to multiply 5 by in order to get 30? Yes, 6 is correct. Then you also have to multiply 8 by 6 as well. That will give you the value of C.
June 27th, 2019, 11:40 AM   #7
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Quote:
 Originally Posted by BRYTBRTRTBRTY … 5/8 = 30/ice-cream cones ice-cream cones = 30*8/5 … is this right …
Hello BRYT…

That's how I learned it (before algebra). The teacher described that method as "multiply on the diagonal and divide by the number not used".

$$\dfrac{5}{8} = \dfrac{30}{x}$$

The numbers 8 and 30 lie on the diagonal, so we multiply them. The number not used is 5, so we divide 8×30 by 5, just like you did.

This method works whenever you know three out of the four numbers in a proportion. Here are some symbolic examples:

$$\dfrac{A}{B} = \dfrac{C}{D}$$

If we know numbers {A,C,D}, then we get B by multiplying on the diagonal and dividing by the number not used. A & D lie on the diagonal, so C is the number not used:

B = (A×D)/C

If we know {B,C,D}, then we get A = (B×C)/D

If we know {A,B,D}, then we get C = (A×D)/B

If we know {A,B,C}, then we get D = (B×C)/A

That last example is what you did above. Cheers!

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