Answer:
Final answer is c. 15
Step-by-step explanation:
We need to find about what is the first term in the sequence for which d = -2 and a7 = 3
We will use nth term formula of arithmetic sequence.

we have been given a7 that means 7th term is 3
so plug n=7, d=-2 and a_n=3 into above formula




Hence final answer is c. 15
37 because you add 13+10=23 7+7=14 and 23+14=37
Answer:
x = 0
y = 5
z = -5.
Step-by-step explanation:
X-5y-z=-20
-2x-y-6z=25
-x-4y-z=-15
Add equation 1 and 3:
-9y - 2z = -35 .......... A
Multiply the first equation by 2:
2x - 10y - 2z = -40
Now add this to equation 2:
-11y -8z = -15.............B
Now multiply equation A by -4:
36y + 8x = 140.........C
Add equations B and C:
25y = 125
y = 5.
Substitute for y in equation A:
-9*5 - 2z = -35
2z = -45 + 35 = - 10
z = -5.
Now find x by substituting for y and z in the first equation:
x - 5(5) - (-5) = -20
x - 20 = -20
x = 0.
Answer:
a. 25
Step-by-step explanation:
Note that the specifically state that they are vertical angles. This means that the two measurements should equal each other. Set the two expressions equal to each other, and isolate the x. Note the equal sign, what you do to one side, you do to the other:
3x = x + 50
Subtract x from both sides to isolate the x:
3x (-x) = x (-x) + 50
3x - x = 50
2x = 50
Isolate the x, divide 2 from both sides:
(2x)/2 = (50)/2
x = 50/2
x = 25
x = 25, or (a) 25 is your answer.
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I believe the answer would be 6:5 because you divide both 18 and 15 by 3.