Answer:
The set of natural numbers is the set of all positive integers, then this set is:
{1, 2, 3, ...}
and the 24th letter of the alphabet is x
Now we want to write the expression given in the sentence "It is one more than the sum of the first three natural numbers, followed by the 24th letter of the alphabet"
We can "break" this in parts, so it is easier to understand.
Then:
"...the sum of the first 3 natural numbers..."
is:
1 + 2 + 3
Then:
"...the sum of the first 3 natural numbers, followed by the 24th letter of the alphabet"
This can be written as:
(1 + 2 + 3) + x
Now we can analyze the complete sentence:
"It is one more than the sum of the first three natural numbers, followed by the 24th letter of the alphabet"
This is equal to the expression we found above plus one, then we can write this as:
[(1 + 2 + 3) + x] + 1
[6 + x] + 1
6 + x + 1
7 + x
