Answer:
9/c or c/9
Step-by-step explanation:
We know in these kind of triangles that have a 90 degrees angle, we can do:

so the first question:

and then:

so , when you want to rationalize , usually you must multiply the irrational factor as 1:

so , now multiply:

in the next question,we know negative numbers in radical don't have any solution so 2 is correct,
Answer:
This is an identity or infinite solutions
Step-by-step explanation:
10x - 12y = 22
5x - 6y = 11
-2(5x - 6y = 11 )
-10x + 12y = -22
10x - 12y = 22
0=0
Identity solution
Sydney has 10 because 30 is 3 times as many as 10 and then the extra 6 is the one you added when it says 6 more than three times