I dont really understand though.. do you have alternative ways?

The idea is that they are filling a tank with water using 2 different taps that have different flow rate, one flow at a rate x litre per min the other x+5(fastr)
Part 1 is asking how long it will take to fill up the tank using only 1 of the 2 taps.
Similar to speed=dist /time. Now is speed of tap=volume of tank/time taken to fill it

After forming the 2 equations in part 1, form a relationship between them such that u can manipulate the equations to form what they want in part 2