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

[EX Q]: Problem: if one - third of one - fourth of a number is 18 , then 3 - tenth of that number is : a . 35
[EX A]: 64.8

[EX Q]: Problem: if a - b = 6 and a 2 + b 2 = 50 , find the value of ab .
[EX A]: a ) 7

[EX Q]: Problem: if it is assumed that 60 percent of those who receive a questionnaire by mail will respond and 240 responses are needed , what is the minimum number of questionnaires that should be mailed ?
[EX A]:
400