to make the proportion we make the ratio of the similar sides
For example
4/8 = 12/x
or we can write it as 4/12 = 8/x
or 12/x = 4/8
So last option is correct
For a you have to solve 2 solutions , first 2x=12
6=x then you plug that back in, 12+8y=12
8y=0
y=0
(6,0)
The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable, but we can work out its value if we try!
Median is just the middle number. If you put all the numbers in order from least to greatest:
4,5,6,7,8,9,10
Then you can find the one in the middle. In this case it’s 7.