Is it necessary
Can I get it cheaper elsewhere
Will it last a while
These are just 3 I came up with. I do not know if they are what your teacher would have put.
Answer: Raju travels at a higher speed.
Step-by-step explanation:

Speed inversely proportional to time.
As time taken to cover a particular distance decreases the speed will increase.
Raju covers a certain distance in 1 hour.
Sham covers the same distance in 2 hours.
1< 2
Thus Raju travels at a higher speed.
Because + and - make - which makes you left with 3-5 which equals to -2 because it gets negative.
The first thing any good mathematician does is convert the measurements to the same unit as what the question is asking. In this problem, it states that the pool fills at a rate of 20 cubic meters per hour. Just keep in mind that an hour is 60 minutes.
The next step is to see how many cubic meters will cost $300. This can be done by dividing 300 by 10. This gets you 30 cubic meters of water.
You already know that 60 minutes is 20 cubic meters of water. That leaves the remaining 10 cubic meters of water. By dividing the rate given, you get that 30 minutes is 10 cubic meters of water. Add the 60 and 30 together to get 90 minutes.
It will take 90 minutes for the pump to use $300.
4 = y - 4
You need to add 4 on each side and you will get 8 which means that y is equal to 8.
4 = y - 4
+4 +4
8=y