Help with question

[Crackle]

I think I have got it, you need to do a sum with all the answers to see which is nearest 60%
So total power is
a) 50 / 134 x100 =37%
b) 50 / 80 x 100 = 62.5%
c) 50 / 83 x 100 = 60.2% ***
d) 50 / 70 x 100 = 71.4%

Is there an easier way rather than going through all the scenarios.

Thanks
Mike