Okay.....
Ieda bakes... 73 Cupcakes.
Melody eats 5.
$${\mathtt{73}}{\mathtt{\,-\,}}{\mathtt{5}} = {\mathtt{68}}$$
So Ieda is left with 68 Cupcakes now.
Now you say that, Ieda then divides them into 13 containers equally...? Okay...
So... Providing it must be equal in all containers, you will have some leftovers.
$${\frac{{\mathtt{73}}}{{\mathtt{13}}}} = {\mathtt{5.615\: \!384\: \!615\: \!384\: \!615\: \!4}}$$
So.... Now rounding that to the last full number... 5 Cupcakes per Container.
So... $${\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{13}} = {\mathtt{65}}$$
So Ieda has 65 cupcakes that is packed away equally. And we have 3 left.
.....More for Melody to eat....