Question

A tank is 4/5 full of water. if 40 gal more water are needed to fill the tank completely, find the capacity of the tank.

Answer 1

Let the capacity of the whole tank be 1
capacity of the tank to be filled (1-4/5)
=1/5
capacity of the tank to be filled is given =40 gallons that is 1/5th portion of the tank is 40 gallons
if 1/5th portion is 40 gallons, then 4/5th portion = 1/5 *4/5th
                                                                           =40 * 4
                                                                            =160 gallons
adding the two 160+40=200 gallons
therefore the total capacity of the tank is 200 gallons