The step after the given would be subtraction
In Perpendicular product of slope is -1 so slope of y=2x-4 is 2 and 2*m=-1 m= -1/2 so y= -1/2x -4
Let
be the random variable for the number of marks a given student receives on the exam.
10% of students obtain more than 75 marks, so

where
follows a standard normal distribution. The critical value for an upper-tail probability of 10% is

where
denotes the CDF of
, and
denotes the inverse CDF. We have

Similarly, because 20% of students obtain less than 40 marks, we have

so that

Then
are such that


and we find

Answer:
Perimeter = 10x + 8 units.
Area = 6x^2 + 13x - 5 units^2.
Step-by-step explanation:
The perimeter is 2*length + 2*breadth
= 2(2x + 5) + 2(3x - 1)
= 4x + 10 + 6x - 2
= 10x + 8 units.
The area = length * breadth
= (2x + 5)(3x - 1)
= 6x^2 - 2x + 15x - 5
= 6x^2 + 13x - 5 units^2.