One number is 4 more than another, and their sum is 60. what is the smaller number?

According to your question, there are 2 unknown numbers mentioned. Let the 2 unknown numbers be represented by the variables x & y, then x is considered to be one of the numbers being more than y by the addition of 4, .ie. x = 4 + y --- (1) The sum of the 2 numbers is 60, i.e. x + y = 60 --- (2) To find the smaller number, we solve eqn (1) & (2) using the concept of substitution, i.e. substitute 4 + y for x in eqn (2), i.e. 4 + y + y = 60 4 + 2y = 60 2y = 60 - 4 2y = 56 y = 28 ...Ans. Recall that x is more than y by 4, then 28 is the smaller number.