Hello for the millionth time again, need help on this badly, pls.

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

Atorch and a battery cost 2.50 altogether.the torch costs 1.50 more than the battery.what fraction of the total price is the torch? give your answer in its simplest form.

Write an expression that is equivalent to ( 3+14)+27.