Hello!
The formula for finding area is l × w
If the area is 19 ½ inches and it was 3 ¼ inches wide, then the length will be 19 ½ ÷ 3 ¼ (Area ÷ Width)

Change both to improper fraction



Keep 39/2
Change ÷ to ×
Flip 13/4 = 4/13

Lets get an example, for this example lets use 24/30 x 30/60
Without dividing out GCFs you would get 24x12 over 30 x 60 which is 288/1800
With dividing out GCFs you get 2/1 x 5/1 Which is 7 :)
For 10 here is the answer and for 9 i’ll reply to my comment
Answer:
Step-by-step explanation:
4 + 2x < 6 + 6x
4 - 4x < 6
-4x < 2
x > -1/2