Answer:
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
