If we want to simplify Algebraic Fractions:
We have to take a look at the numerator and the denominator
Why? Because to simplify we need to have a common multiple.
When we find the common multiple, we now know by which factor we have to break down the fraction in the numerator and the denominator
I have some examples attached below for help.
Answer:
1. 
2. 
Step-by-step explanation:
Given
Variation: inverse Proportion
y = 7, x = 9
Required
- Write an equation connecting y and x
- Find y when x = 21
Given that thee variation is inversely proportional;
This implies that

Convert variation to equation
----------- Equation 1
Where k is the constant of variation
Substitute 7 for y and 9 for x in equation 1

Multiply both sides by 9


Substitute 63 for k in equation 1

Multiply both sides by x


Hence, the equation connecting x and y is 
Solving for when x = 21
Substitute 21 for x in the above equation

Divide both sides by 21


R =4/3 (p-q)
3 x r = 4 (p-q)
(3 x r)/4 = p - q
(3 x r)/4 - q = p
The rectangle on the right is 81 and the rectangle on the left is 24. I don't really know about the second one sorry, but I hope this helped.