Well, I cannot say its exactly a short method, but looking at the options one can surmise the ans.
Take 100 as base figure. Now try the options.
You can say that "The drop produced by less revenue by Car sales" MUST BE Surpassed by" The gain from Truck Sales". to achieve the Net Gain Effect.
i.e the proportion of Truck Revenue has to be greater than Car Revenue.
By this you can directly eliminate C,D and E. Now for remaining options,
Say we start from B. Then 4:5 will mean :
Rev 400 for cars and Rev 500 for Trucks
Calculate 11% @ 400 and 7% @500. We just have to ensure that
7% @ Trucks MUST BE > 11% @ Cars. Right !!!
"The way to succeed is to double your error rate."
"Most people who succeed in the face of seemingly impossible conditions are people who simply don't know how to quit."