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.
