Find the sum. 10 + 12 + 14 + ... + 80
1 answer:
Answer:
1620
Step-by-step explanation:
The amount of even integers between 10 and 80 inclusive is 36 (5 for each interval of 10 [e.g., 10-19 has 5, 20-29 has 5] and one extra for 80).
Since the numbers are consecutive even numbers, we can use the fact that the sum of the numbers is equal to the average of the numbers, times the number of numbers.
The average of the numbers is 45, since . We can use only the two outer numbers to determine the average since the numbers are all evenly spaced as they are consecutive even numbers.
, so the sum is 1620.
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Answer:
3, -8
(x is equal to 3 and y is equal to -8)
Step-by-step explanation:
<u>The system:</u>
{ 7x=-67-11y
{ 5x=-73-11y
<u>Finding a value for x:</u>
7x=-67-11y -> x = -
<u>Solving for y by plugging in our x:</u>
[Equation] 5x = -73 -11y
[Plug-in] 5( -
) = -73 -11y
[Distribute the 5] -
= -73 -11y
[Multiply by 7] 7 ( -
) = (-73 -11y) 7
[Simplify] -335 - 55y = -511 - 77y
[Add 335 and 77y to both sides] 22y = -176
[Divide by 22] y = -8
<u>Plug in our y to solve for x:</u>
5x = -73 -11y
5x = -73 -11(-8)
5x = -73 + 88
5x = 15
x = 3
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather