if n divided by 5 has a remainder of 4 , what is the remainder when 3 times n is divided by 5 ?
"as per question = > n = 5 p + 4 for some integer p hence 3 n = > 15 q + 12 but again , 12 can be divided by 5 to get remainder 2 for some integer q hence d"
multiply(3, 4)