Here's a pattern to consider:
1+100=101
2+99=101
3+98=101
4+97=101
5+96=101
.....
This question relates to the discovery of Gauss, a mathematician. He found out that if you split 100 from 1-50 and 51-100, you could add them from each end to get a sum of 101. As there are 50 sets of addition, then the total is 50×101=5050
So, the sum of the first 100 positive integers is 5050.
Quick note
We can use a formula to find out the sum of an arithmetic series:

Where s is the sum of the series and n is the number of terms in the series. It works for the above problem.
Answer: the leg x would equal 76.8, or 77 rounded. The actual number would be 76.8374908492.
Answer:
y=5x+4
Step-by-step explanation:
First get slope:
(4-9)/(0-1) = -5/-1 = 5
The y-intercept is where the graph hits the y-axis. That is also the point on the graph where x = 0. We are already given that, with point (0,4).
The y-intercept is 4.
y = mx +b, m is slope and b is the intercept.
y = 5x +4
I have solved the answer in the pic below, hope it helpss!!!!