Answer:
60 cups
Step-by-step explanation:
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Answer:
a. 
b. 
Step-by-step explanation:
I attach the diagram of the new water tank.
a. In order to find the volume of the tank in cubic feet, we will need to calculate the volume of a cylinder. We know that its base measures
and its height is
.
The volume ''V'' of a cylinder is :

Where ''
'' is the diameter of the base and ''
'' is the height of the cylinder.
If we replace all the data in the equation :

We found out that the volume of the tank in cubic feet is 
b. We know that 1 cubic foot of water is equal to 7.5 gallons. To find the amount of gallons that the new tank can hold, we need to do an unit conversion.
This equivalence is given to us :
⇒ Using the equivalence ⇒

Finally, the new tank will hold
of water.
Let x be the age of ishaan so the age of ben will be 12+x. the equation will become x=x+12
Going 3 years back, the age of ishaan was x-3 so that of ben would be x+12-3 before 3 years. at that time the age of ben was 4 times the age of ishaan. it means x+12-3(the age of ben)=4(x-3(the age of ishaan))
solving this equation, we get the answer x=7. this is the age of ishaan in the present.