Answer:
3:5 = 30:50 because it is ratio 3 x 10 = 30 5 x 10 = 50
40-15=25 students not on student council
25/40 = .625 decimal
multiply by 100 to get percent
62.5% of students are not on student council
Estimating:
15 rounds to 20 and 40 rounds to 50
40% are in student council and that leaves roughly 60% not in student council.
Answer:
the length of the rectangle is, 21 in.
Step-by-step explanation:
Area of the rectangle(A) is given by:
.....[1]
where,
l is the length of the rectangle
w is the width of the rectangle.
As per the statement:
The width of a rectangle is 9 in. shorter than its length.
⇒
It is also given that:
The area of the rectangle is 252 in².
⇒A = 252 in².
Substitute in [1] we have;

⇒
⇒
Factorize this equation:
Split the middle term;
⇒
⇒
⇒
By zero product property we have;
and 
⇒
and 
Since, length cannot be in negative
⇒
Therefore, the length of the rectangle is, 21 inches.
Refer to the attached image.
Given the rectangle ABCD of length 'l' and height 'h'.
Therefore, CD=AB = 'l' and BC = AD = 'h'
We have to determine the area of triangle AEF.
Area of triangle AEF = Area of rectangle ABCD - Area of triangle ADF - Area of triangle ECF - Area of triangle ABE
Area of triangle ADF = 
= 
= 

Area of triangle ECF = 
= 
= 

Area of triangle ABE = 
= 
= 

Now, area of triangle AEF =
Area of rectangle ABCD - Area of triangle ADF - Area of triangle ECF - Area of triangle ABE
= 
= 
=
=

= 27 units
Therefore, the area of triangle AEF is 27 units.
146.74 because 42% of 253 is 106.26, and take that away from 253 = 146.74