Evaluate c7, 5).

a. 21

b. 42

c. 1,008

C(n, r) = (n!)/(r!*(n-r)!) is the combination formula

C(7, 5) = (7!)/(5!*(7-5)!)

C(7, 5) = (7!)/(5!*2!)

C(7, 5) = (7*6*5!)/(5!*2!)

C(7, 5) = (7*6)/(2!) note the "5!" terms divided and canceled

C(7, 5) = (7*6)/(2*1)

C(7, 5) = 42/2

C(7, 5) = 21

hello :

by applying the distributive property :

6 × 4.3 = 6 × ( 4 + 0.3 )

            =   (6 ×   4) + (6 ×   0.3)

            = 24 + 1.8

6 × 4.3 = 25.8