# Problem of the Week Problem E Let’s All Ride a Bike

Grayson’s Groupcycles rents bikes with multiple seats for large groups of people. They rent $$7$$-seater, $$13$$-seater, and $$25$$-seater bikes. A group of $$14$$ people could fit on two $$7$$-seater bikes, however a group of $$15$$ people could not fit exactly on any of the bikes since no combination of bikes have exactly $$15$$ seats.

What is the largest group size that cannot fit exactly on any combination of bikes from Grayson’s Groupcycles?