# Math Help - coprime numbers

1. ## coprime numbers

2m-3 and 10m-15 are coprime integers.Which of the choices from below
is coprime with each one of the numbers?
a)3m-1
b)m+4
c)2m+6
d)m+3
e)5m

First of all both numbers are not coprime. When we divide them with
each other we get 5 or 1/5.

2. ## Re: coprime numbers

10m-15 = 5(2m-3), so the second is a multiple of the first. I agree they are not coprime.

3. ## Re: coprime numbers

in order for 2m-3 and 10-15=5(2m-3) to be coprime m=2.

Thus we have 1 and 5 as our two numbers. The values corresponding to the answers are

a)5
b)6
c)10
d)5
e)10

and clearly of these only 6 is coprime to to 5 so (b) must be the answer.

many thanks