Susan P. answered 03/19/19
I'm great at analyzing what you do and don't understand!
Hi, Zoe. I think you left a verb out of the problem: I believe Manuel's brother left 1/4 of the crackers on the plate. Let me know if I got this wrong.
The trick is recognizing when to use what is left and when to use what was eaten.
If Manuel ate 1/3 of the crackers, then 2/3 of the crackers were left for Manuel's brother. Make c=the number of crackers at the beginning of the problem.
2x is the number of crackers Manuel's brother has to feast on
3
Since I am assuming that Manuel's brother left 1/4 of the remaining crackers behind, this would be
1 times 2x = 5
4 3
and all of that equals the 5 leftover crackers.
To handles fractions like this in algebra, multiply by the reciprocal (which is the fraction upside down.)
1 times 2 = 2
4 3 12
So we need to multiply both sides of the equation by 12/2, because that is the fraction 2/12 upside down.
5 times 12/2 = 60/2 = 30.
So there should be 30 crackers on the plate at the beginning of the problem, but only if I guessed correctly about what was missing from the problem.