Kevin had 20 more stamps than Ronny. Ronny gave Kevin 1 stamp. How many more stamps did Kevin have than Ronny in the end?
Suppose Kevin has N syamps and Ronnie has N + 20 stamps
So after the trade
Ronnie - Kevin =
( N + 20 + 1) - ( N - 1) =
20 + 1 - (-1) = 20 + 2 = 22
Kevin had 22 more stamps
20 + 1 + 1 = 22
kevin had 22 stamps than Ronny in the end
