Answer:
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)
10x + 2y - 6 = 0
Multiply 5x + y - 3 = 0 by 2
2(5x + y - 3 = 0) = 10x + 2y - 6 = 0
You can set them equal to each other so -3x+4=4x-10 and then you add 3x and 10 on both sides and get7x=14 and then divided both sides by 7 and get x = 2 and check by plugging in and you get -2 for y on both so solution is x=2
