A colony of ants carried away 10 of your muffins. That was 2/5 of all of them! How many are left?

2/5=0.4=40%

If 40%=10 muffins, then 20 muffins=80%

100%-80%=20%

We know that 40%=10 muffin, so 20% out of 10 muffins will be 5.

If 25 muffins was at the beginning, and a colony of ants carried away 10 of them, then 15 muffins are left.