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

[EX Q]: Problem: if the cost price of 50 articles is equal to the selling price of 40 articles , then the gain or loss percent is ?
[EX A]: 25 %

[EX Q]: Problem: in township k , 1 / 5 of the housing units are equipped with cable television . if 1 / 10 of the housing units , including 1 / 3 of those that are equipped with cable television , are equipped with videocassette recorders , what fraction of the housing units have neither cable television nor videocassette recorders ?
[EX A]: 23 / 30

[EX Q]: Problem: the population of locusts in a certain swarm doubles every two hours . if 4 hours ago there were 1,000 locusts in the swarm , in approximately how many hours will the swarm population exceed 128,000 locusts ?
[EX A]:
10