19.(3/4)/(1/32)=24
20.(3/4)/(1/14)=21/2
21.(1/2)/(1/72)=36
Option B:
The expression equivalent to |a| ≤ 5 is a ≥ -5 and a ≤ 5.
Solution:
Given expression: 
To find the equivalent expression for the given expression.
Apply absolute value rule:
<em>If |x| ≤ m then -m ≤ x ≤ m.</em>

⇒ -5 ≤ a ≤ 5
⇒ -5 ≤ a and a ≤ 5
Switch the sides, we get
⇒ a ≥ -5 and a ≤ 5
The expression equivalent to |a| ≤ 5 is a ≥ -5 and a ≤ 5.
Option B is the correct answer.
Answer:
Step-by-step explanation:
1. (a+3)(a-3) = a²+3a-3a-9 = a²-9
2. a linear equation consists of a polynomial of degree one.
4m = 12x + 40
8x + 8x + 12x + 40 + 4m = 360
28x + 40 + 12x + 40 = 360
x = 7
m = 12(7) + 40 = 124