Step-by-step explanation:

Answer:
The answer is 85
Step-by-step explanation:
The equation used to find the sum of an arithmetic series is: (n/2) * (a1 + an).
n in this case is 10 (the number of numbers in the series)
an is 22 (plug in 10 to the expression 3n-8)
and a1 is -5 (plug in 1 to the expression 3n-8)
so when you plug everything in to the final equation, you get
(10/2) * (-5 + 22)
5 * 17
85
Answer:
We have the equation A*C = A
Now, as both sides of the equality are the same thing, we can do the same operation to both sides and the equality will remain true.
We can divide both sides by A and get:
(A*C)/A = A/A
C = 1
So here we finded the value of A.
If A and C are matrices, then C is the identity matrix.
A= (h(a+b))/2
multiply each side by 2
2A = (h(a+b))
divide each side by h
2A/h = a+b
subtract a from each side
2A/h -a = b