The task is to generate the correct answer for a given math problem.

Ex Input:
Problem: the ratio of the radius of two circles is 1 : 3 , and then the ratio of their areas is ?

Ex Output:
1 : 9


Ex Input:
Problem: there are 7 executives , including the ceo and cfo , that are asked to form a small team of 4 members . however , the ceo and cfo may not both be assigned to the team . given this constraint , how many ways are there to form the team ?

Ex Output:
25


Ex Input:
Problem: a man swims downstream 96 km and upstream 64 km taking 4 hours each time ; what is the speed of the current ?

Ex Output:

4