A rancher has a square cow pen with side length x. He deicdes to change the shape of the pen while still using
the same amount of fencing materials. The equation
(x + 10)(x - 10) = 300 represents the relationship
of the new side lengths (in feet) of the pen and its area
(in square feet).
a. If 300 represents the area of the new cow pen, what
do the expressions (r + 10) and (x - 10) each
represent?

The answer is in the image 

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

30% of 420 are first year students

first year students = (30/100 )*420

=126 students

Student who are not in first year = 420-126

=294 students  

Area of rectangle= L*b

here,

L=12.4 cm

b= 8.8 cm

A= L*b

= 12.4 * 8.8 = 109.12 cm^2

Given height of gymnasium is 5/6 height of 30 foot ball

therefore height of gymnasium=5/6 * 30

=25 feet

The solution is given below

The answer is in the image 

(​1 or 7) ; number of possible outcome = 2

(a, e,​ i, o, or​ u) ; number of possible outcome = 5

So,

Number of possible outcomes = 2 x 5

Number of possible outcome =10

Total fabric purchased = 1 1/4 = 5/4

Fabric used = 3/4

Fabric left = 5/4 - 3/4

                 = 2/4

                 =1/2 yard