Of the first graders who were asked, 1/6 like math best, 2/3 liked reading best, and 12 liked science best. How many were asked their favorite subject?
first we represent unknowns using variables,
let x = the number of students asked
then we set up the equation,, since the given were the fractional parts of the total number, we represent each part as
(1/6)x : the number of students who like math
(2/3)x : the number of students who like reading
thus,
(1/6)x + (2/3)x + 12 = x
(1/6)x + (4/6)x + 12 = x
(5/6)x + 12 = x
12 = x - (5/6)x
12 = (1/6)x
x = 72 students
hope this helps~ :)