B is your answer.
Because 7 times 8 is 56 and 7 times 3 is 21.
The answer is c. I chose the answer c because y=5/2x(I think you forgot to put the x in the question) filled in with the numbers are true while a, b, and d aren't true if filled with 10 and 4.
So use cancelation
multiply first equation by 2
2x+8y=10
times 2
4x+16y=20
now add
4x+16y=20
<u>-4x-9y=-13 +
</u>0x+7y=7
7y=7
divide by 7
y=1
subsittue
2x+8y=10
2x+8(1)=10
2x+8=10
subtract 8 from both sides
2x=2
divide by 2
x=1
x=1
y=1
<u />
Answer: Choice C
(4, 18)
=========================================
Explanation:
One point shown on the graph is (2,9)
If we double each x and y coordinate, then
We go from (2,9) to (4,18)
Plotting this point on the graph will be on the same line as the other points.
Or you could note that y/x = 9/2 = 18/4 = 4.5