Question

If r is the remainder when the positive integer n is divided by 7, what is the value of r?

Answer 1

Answer:

Step-by-step explanation:

Given that When n is divided by 21, the remainder is an odd number.

i.e. $n=21m+k$ where m is an integer and k a positive integer <21

When n is divided by 28, the remainder is 3

$n=28c+3$, where c is a positive integer

This can be written as

$n=4(7c)+3\\n=7(4c)+3$

Since n is giving odd remainder when divided by 21,

we get r =3 as n is a multiple of 7 +3