Answer:
[tex]time=40/3hours\approx 13.3hours[/tex]
Step-by-step explanation:
The rates are additive: you can calculate the inlet rate and the outlet rate and add them algebraically, i.e. the inlet rate will be positive and the outlet rate will be negative.
1. Inlet rate:
[tex]1vat/5hours[/tex]
2. Outlet rate:
[tex]1vat/8hours[/tex]
3. Net rate:
[tex]\text{Inlet rate - outlet rate}=1vat/5hours-1vat/8hours\\\\ \text{Net rate}=(8-5)vat/40hour=3vat/40hour=(3/40)vat/hour[/tex]
4. Time to fill the vat
[tex]rate=amount/time\implies time=amount/rate\\ \\ time=1vat/(3vat/40hour)[/tex]
[tex]time=40/3hours\approx 13.3hours[/tex]