Question

Please help me with this problem​

Answer 1

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

Answer 2

-5/2 as perpendicular lines have inverse slopes