estimate:\n20 is 22% of what number?\na 40\nb 50\nc 75\nd 100

Explanation:

Step1: Define the unknown number

Let the unknown number be $x$.

Step2: Set up percentage equation

$22% \times x = 20$, or $0.22x = 20$

Step3: Solve for estimated $x$

Since $22% \approx 20% = 0.2$, estimate $x \approx \frac{20}{0.2} = 100$

Answer:

D. 100