Using substitution:
first you have to express one variable in terms of the other, in this we can express y in terms of x:

Since both expressions are equal to y, you have to equal both expressions like this:

Now you can solve the equation:

Knowing x=10, you can use any of the expressions we found before to find y. In this case I'm going to use y= -x+9 because it's simpler but boy should give you the same result

So, the answer is x=10 and y=-1
Answer:
2
Step-by-step explanation:
Answer:
(b) 1:9
(c) 1:8
Step-by-step explanation:
(b) x*y : kx*ky, so 1:k² with k=3 is 1:9
(c) Assuming the rectangles get a z dimension, the volumes would have a ratio of xyz : xkykzk = xyz : xyzk³ = 1 : k³. With k=2 that is 1:8. But the z was never introduced so this is a bit inconclusive.
It's simple you've been told that correct answers equals 6/7 and she did all the questions. Therefore the incorrect answers equals 1/7, which is 4. So just times 4 by 7. 4 x 7 = 28. 28 questions on the quiz.