Asked by ruth

the H.C.Of two numbers is 7and their L.C.M is 140.If one of the numbers is 28,find the other number

Answers

Answered by Steve
the two numbers are 7a and 7b
where a & b have no common factors
The LCM is ab/7
So, if 7a=28, 28b/7 = 140
b = 140*7/28 = 20/4 = 5
check: LCM(28,35) = 140
Answered by Reiny
140 = 2*2*5*7
28 = 2*2*7

140/28 = 35 , both 140 and 28 have a factor of 7, but not the 5
<b>So it looks like 35 is the other number.</b>

check:
35 = 5*7
28 = 4*7

Highest common factor is 7
LCM = 5*7*4 = 140

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