This is correct he is not wrong the answer is A.

it just so happen that √2 is an irrational number, so any product with it as a factor, will yield an irrational number as well.
factoid: Ancient Greeks were scared of irrational numbers, and they steered clear from √2.
Answer:
(2,-2)
Step-by-step explanation:
The first step is to substitute y in the first equation with the right side of the second equation because they both equal to y.
-3x+4 = 4x-10
-3x-4x+4-4 = 4x-4x-10-4
-7x = -14
-7x/-7 = -14/-7
x = 2
Plugin 2 for x for either equation to solve for y, I'll be using the second equation, but either one is fine.
y = 4(2)-10
y = 8-10
y = -2
Plugin x = 2 and y = -2 into (x,y), and you get (2,-2)
Let n be old painters time. Then the new painters are 2n. So:
1/n+1/2n=1/6
2+1=2n/6
2n=18
n=9
The old painters take 9 hours; the new ones take 18
☺☺☺☺