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

[Q]: Problem: students at a school were on average 180 cm tall . the average female height was 170 cm , and the average male height was 184 cms . what was the ratio a of men to women ?
[A]: 5 : 2


[Q]: Problem: if a - b = 5 and a 2 + b 2 = 31 , find the value of ab .
[A]: 3


[Q]: Problem: farm tax is levied on the 45 % of the cultivated land . the tax department collected total $ 3840 through the farm tax from the village of mr . willam . mr . willam paid only $ 480 as farm tax . the percentage of total land of mr . willam over the total taxable land of the village is :
[A]:
27.78 %