Number of jobs=1
Time:
Since ‘x’ is given as a variable in the choices, we should reserve it for Kate and use ‘y’ for Jean as follows:
Kate: => x
Jean: => y
But y = x - 5
Combined rate:
1/x+ 1/y
= (x + y)/(xy)
Number of jobs done:
Number of days X combined rate = number of jobs
6 [(x + y)/(xy)] = 1
6x + 6y = xy
6x + 6(x - 5) = x(x - 5)
6x + 6x - 30 = x² - 5x
12x - 30 = x² - 5x
x² - 17x + 30 = 0
Therefore, the answer would be A.
