Find the sum of all integers between 84 and 719 which are exactly divisible by 5

50,800

Step-by-step explanation:

The first integer between 84 and 719 that's divisible by 5 is 85.

The last integer between 84 and 719 that's divisible by 5 is 715.

The sum of an arithmetic sequence is:

S = n (a₁ + a) / 2

where n is the number of terms, a₁ is the first term, and a is the last term.

To find the number of terms:

n = (a - a₁) / d + 1

where d is the common difference.

Here, a = 715, a₁ = 85, and d = 5.

n = (715 - 85) / 5 + 1

n = 127

S = 127 (85 + 715) / 2

S = 50,800