If 145 guests account for 25% then to get the remaining 75% you divide that number of guests by 25% and then multiply by 100 which is your 145 vegetarian guests plus 580. So 725 guests altogether.

Haven't done percentage calculations since my Chemistry days so does anyone want to verify that?

Edit* Going by the way I did it I wasn't sure if 580 was 75% of all people or 100%.

 

its 580 if 145 is 25%


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I am really bad at maths as you can tell. I need it explained as if you're talking to a child, really basic. How do you know that 145 = 25%

If people feel like explaining; probably got better things to do. I can always ask the teacher

 

Well you know the proportions to the whole of the other choices and you know the whole must be 100% so you just have to subtract to find the proportion for the vegetarian. 1/5 is 20% and 11/20 is 55% which net to 75% and 100% - 75% is 25%. So if 145 is 25% and if you want to know 100% then multiply 145 X 4 = 580. You don't even really need to convert it to algebra or anything to solve it.

Are you taking the GMAT? This looks like a GMAT type question.

Also, why the heck does Meg have so many vegetarian friends? Did she grow up on a commune or something?

 

1/5 of guests chose beef and 11/20 of guests chose chicken.

1/5 is equal to 4/20.

So if you add the guests who chose beef and chicken, that's 4/20 + 11/20, which is 15/20.

15/20 is equal to 3/4. Which means that 1/4 people ordered vegetarian.

If 145 is 1/4, we multiply it by 4 to get the whole amount of guests, and that's 580.

 

where n is the number of guests
b is orders of beef
c is orders of chicken
v is orders of vegetarian

0.2n=b
0.55n=c
v=n - b - c
v=(1-0.2-0.55)n
v=0.25n

v=145
0.25n=145
n=580

 

1/5 = 4/20 chose beef

11/20 chose chicken

So adding those together shows 15/20 chose something other than vegetarian. Meaning 5/20 chose vegetarian.

So if 145 chose vegetarian. 5/20 of x= 145

145 / .25 = 580 guests

Basically what Veron said lol

 

I did this on a calculator (but I can do this without a calculator as well)

(1/5) + (11/20) = 0.75

Remaining = 0.25 => (145)

145 x 4 = 580

But I wasn't sure, what I'm doing is correct or not!

I checked others answers and it seems correct... Wahoo!

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At first, I tried something else which seems wrong!

Like I divided the 11/20 with 5 which is 2.22/4 - to make the base 5 and then got confused!

 

Thanks everyone who replied! Y'all are so helpful