Answer:
y = 7 - 2x/3
Step-by-step explanation:
Make the y alone, so 3y = -2x+21
Divide everything else by 3, so y = -2x/3 +7
You end with the answer of y= 7-2x+3
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,
Here is the answer of the given question above. According to the puzzle given by Crafty grandma Edith, which was answered by her 6-year-old granddaughter during their thanksgiving gathering, the correct answer of 9183 would be number 3. Hope this is the answer that you are looking for. Thanks for posting!