Ann made a 3 -step staircase using 18 toothpicks as shown in the figure. How many toothpicks does she need to add to complete a 5-step staircase?
Answer Choices
A. 9
B. 18
C. 20
D. 22
E. 24
Ann made a 3 -step staircase using 18 toothpicks as shown in the figure. How many toothpicks does she need to add to complete a 5-step staircase?
Answer Choices
A. 9
B. 18
C. 20
D. 22
E. 24