Intermediate value theorem

Our professor only briefly skimmed over the IVT, and he assigned a problem for homework, and I have no clue what to do.

a) Suppose that *F* and *G* are two continuous functions on an interval a __<__ x __<__ b, and that *F*(*a*) __<__ *G*(a) but *F*(*b*) __>__ *G*(*b*). Show that the equation *F*(*x*) = *G*(*x*) is satisfied for some *x* on the interval.

b) By applying a), show it is possible to cut any circular cake through its exact center so that the two halves have exactly the same amount (area) of icing, no matter how unevenly the cake may have been iced.