To build a school;
20 workers -> 18 days.
So 1 worker -> 18/20 days.
So; 12 workers -> (12×18)/20 days.
-> (12×9)/10 days
->10.8 days.
so 10.8 days is your answer.
Hope it helps...
Regards;
Leukonov/Olegion
True the circle is a congruent to the radius of an inscribed regular polygon inside the circle
I think the equation is
y=-1/3x +10/3
(1/3x+y=10/3)•3
x+3y=10, is the answer

subtract 1 from both sides

divide by 2 on both sided