Lcm

[rashel]

If the least common multiple of positive integer m and n is 120, and m:n=3:4, what is the greatest common factor of m and n?
(A) 3
(B) 5
(C) 6
(D) 10
(E) 12

[krovvidy]

LCM(m,n) = 120
i.e., LCM(3k,4k) = 3*4*10 ----[m=3k & n=4k since m:n = 3:4]
i.e., k=10 ... So, m=30 & n=40

GCF(m,n) = GCF(30,40) = 10 (D)

[mannu08]

cool ans krovvidy