Bob is making sandwiches for a school picnic. He is making these types: ham, cheese, and turkey. So far, he has made 12 ham sandwiches, 20 turkey, and 4 cheese. What combination can he make so that exactly 1/5 of the sandwiches are cheese?

If he makes x more cheese sandwiches, then

(12+20+4+x) = 5(4+x)
x = 4

check: 4+4=8 cheese out of 40 total.

You can try other settings as well.

he is correct ^

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To find the combination of sandwiches that satisfies the given condition, we need to determine the total number of sandwiches and then calculate 1/5 of that number.

First, let's find the total number of sandwiches Bob has made so far. We add up the numbers of each type of sandwich:
12 ham sandwiches + 20 turkey sandwiches + 4 cheese sandwiches = 36 sandwiches.

Now, we need to figure out what number represents 1/5 (or 20%) of these sandwiches. To do this, we multiply the total number of sandwiches by 1/5:
36 sandwiches * 1/5 = 36/5 = 7.2 sandwiches.

Since we can't have a fraction of a sandwich, we need to find a combination that allows for exactly 7 of the 36 sandwiches to be cheese.

Given that Bob has already made 4 cheese sandwiches, we subtract that number from the desired number of cheese sandwiches:
7 - 4 = 3.

Bob needs to make three more cheese sandwiches to have a combination where exactly 1/5 of the sandwiches are cheese.