If the average weight of students of class A is 32kg and that of class B is 36kg. If 12 students are transferred from class A to class B, the average of class B becomes 35.5kg and that of class A becomes 30.5 kg. What can be the average weight of these transferred students? (a)38.5kg (b)32kg (c)36kg (d)34kg (e)None of the above.

Apologies for the answer above. I believe there is not enough information to solve this question. so the answer may be none of the above. please correct me if I am wrong.

a reduction in the price of petrol by 10% enables a motorist to buy five gallons more for $180.Find the original price of petrol.

Let's say price of petrol per gallon = $x and number of gallons bought earlier for same net price be y x(y) = 180 ---(1) and with a discount of 10%, he/ she can get 5 gallons more ((90/100)x)(y+5) = 180 ---(2), on solving 1 and 2, we get original price to be $4. Cheers.