What is your assignment about
6+21 because when u multiple -1 with -21 it gives u +21
This is a system of equations. The first equation represents the tank being emptied and the second equation represents the tank being filled:
k = -10t + 528
k = 14t
To solve this system of equations, we will use substitution. The second equation says that k is equal to 14t, so we can substitute 14t for k in the first equation.
14t = -10t + 528
24t = 528
t = 22
Now that we have t, we can use it to find k by plugging it in to the second equation:
k = 14(22)
k = 308
So, it will take 22 minutes for both tanks to hold equal amounts of water. They will each hold 308 kiloliters.
Looking at the question we can see that it says:
We should know what these symbols mean:
stands for something less than the other, for example:
We can say that 2 is less than 5 so in a symbolic form it can be written as,
Similarly,
stands for something greater than the other, for example:
We can say that 7 is greater than 5, in a symbolic form it can be written as,
So here, 
means that, 42153 is greater than 35214.
