Question

Datan asks you "Hey Yosief, I have a question for you, if I gives 4 chocolate bars to each child at my party, I will have 38 left. If I give 7 chocolate bars each, I will have 2 chocolate bars left. How many children were there at my birthday party?"

Answer 1

There were `12` children at Datan's birthday party.

Explanation:

Le the number of children at Datan's birthday be `x`.

If he gives `4` chocolate bars to each child at his party i.e. in all `4xx x` and he has `38` left, he must be having

`4xx x+38=4x+38` chocolate bars.

If Datan gives `7` chocolate bars to each child at his party i.e. in all `7xx x` and he has `2` left, he must be having

`7xx x+2=7x+2` chocolate bars.

Hence, as the two should be equal, we have `7x+2=4x+38`

or `7x+2-4x-2=4x+38-4x-2`

or `7x+cancel2-4x-cancel2=cancel(4x)+38-cancel(4x)-2`

i.e. `3x=36` and hence `x=36/3=12`

There were `12` children at Datan's birthday party.