In how many ways can nature select 6 students out of a class of 18 students to get the flu? There are
ways nature can select 6 students out of a class of 18 to get the flu.

Areflection of shape i across the y-axis, followed by a , and then a translation left 6 units and down 4 units confirms congruence between shape i and shape ii. alternatively, a of shape ii about the origin, followed by a reflection across the y-axis, and then a translation right 4 units and up 6 units confirms congruence between shape ii and shape i.