To find the number of terms in the sequence 20, 25, 30, ..., 140, we can use the formula for the nth term of an arithmetic progression:

nth term (Tn) = a + (n - 1) * d

Where:

a is the first term of the sequence (a = 20 in this case).
d is the common difference between consecutive terms (d = 25 - 20 = 5 in this case).
n is the number of terms we want to find.
We need to find the value of n when Tn is equal to 140, as that's the last term in the sequence.

140 = 20 + (n - 1) * 5

Now, solve for n:

140 - 20 = (n - 1) * 5 120 = (n - 1) * 5

Divide both sides by 5:

120/5 = (n - 1) 24 = n - 1

Now, add 1 to both sides:

n = 24 + 1 n = 25

So, there are 25 terms in the sequence 20, 25, 30, ..., 140. The correct answer is 25.