Answer:

Step-by-step explanation:
I don't know if this was the answer you were looking for but there you go, there are many other possibilities you could also use.
First we find the common difference...to do this we subtract the first term from the second term. -7 - (-1) = -7 + 1 = -6
now we are going to find the 10th term
an = a1 + (n-1)*d <== formula for finding any term in arithmetic series
a1 = 1st term, d = common difference, n = term we want to find
now we sub
a10 = -1 + (10 -1) * -6
a10 = -1 + (9 * -6)
a10 = -1 - 54
a10 = - 55
now we will find the sum
Sn = (n (a1+ an)) / 2 <== formula for finding the sum
S10 = (10(-1 - 55))/2
S10 = (10(-56) / 2
S10 = -560/2
S10 = - 280
so the sum of the first 10 numbers is -280
Answer:
215 students
Step-by-step explanation:
500 divided by 2 = 250
250 - 35 each= 215
Answer:
19
Step-by-step explanation:
45-45-90 triangles always have two legs that are the same length, and a hypotenuse that is the length of the leg times sqrt 2.
Given the position of x, we know it is a leg and must be equal to the other leg, which is 19.