In order for two lines to be perpendicular, their slopes must multiply together to equal to negative one
So we do negative one divided by 2/5 to get the slope of the red line
Which is -5/2
To check, we do 2/5 multiplied by -5/2 which equals to -1 so our answer is correct
The origin is 0,0 the y axis is the line going up, the x axis is the line going like this — the top right is quadrant 1 the one below it is quadrant 2 the one beside that is quadrant 3 and the one above that is quadrant 4
For instance take 9; 9x4= 36
So it will be equal
The answer in 4 hope this helps :)