Katrina used 2 5/6 packs of mechanical pencils in the first 2/3 of the year. At what rate is Kelly using mechanical pencils?
A. 1 8/9 packs per year
B. 2 1/6 packs per year
C. 3 1/2 packs per year
D. 4 1/4 packs per year

Katrina is using 21//6 (B) packs per year

d. bc = 12 and ef = 16

step-by-step explanation:

we are given that δabc : δdef such that .

also, it is given that

so, from the options, we need that .

a.

b.

c.  

d.

as, we can see that only option d gives the same ratio as i.e. .

hence, the possible lengths are bc = 12 and ef = 16.