Please help meeeeeeeeeeee

You perimeter is going to be 50. This is because to find perimeter you add all the sides together. For the one side that is missing you need to find the half that is given and go from there. so the missing side is 4 because 7+4 = 11. So in reality it is 11+11+14+14.

At the end of the day 797 lockers were closed.

Step-by-step explanation:

So first of all you need to find out how many even numbers there are from 1-900 (which is 450) so you know that 450 are open. In the 3 multiplication tables every second number is even so you know that half of the 450 lockers that was opened was closed again: this meant that 225 lockers remained open.

You also know that every number in the 4 multiplication tables is the second number in the 2 multiplication tables so half of them are closed but you also know that the 900th locker was opened so now you have 113.

So to conclude you do 900-113 which gives you 797 (this is because 113 is the amount of lockers that is open)