The petrol tank at the local service station has a capacity of 6000l. it is 66.06 percent full. how many litres of petrol are needed?

Since the tank is 66.06% full, it is (100 - 66.06) = 33.94% empty.

Its capacity is 6,000L.  So, in order to fill it to capacity, the service station
must order  33.94% of 6,000L .

               33.94% = 0.3394
               "of" means "times"

0.3394 x 6,000L = 2,036.4 liters needed, to fill the tank to the rim.

Aand b are correctly balanced reactions. they have the same number of atoms in both sides of the reaction