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

Ex Input:
Problem: a and b can together finish a work in 40 days . they worked together for 10 days and then b left . after another 15 days , a finished the remaining work . in how many days a alone can finish the job ?

Ex Output:
2

Ex Input:
Problem: a and b are 90 km apart they start to move each other simultaneously a at speed 10 and b at 5 km / hr if every hour they double their speed what is distance that a pass until he meet b ?

Ex Output:
60 km

Ex Input:
Problem: a company recently conducted a survey and found that 20,000 of its customers live in rural areas . if the number of customers who live in urban areas is 100 percent greater than the number of customers who live in rural areas , how many customers live in urban areas ?

Ex Output:
40,000