Answer
1/3
Work Step by Step
In order to do this problem, recall (1) that addition and subtraction come after multiplication and division in order of operations, (2) that when there is a tie in order of operations, it is done from left to right, and (3) that dividing by a fraction is the same as multiplying by that fraction's reciprocal.
$$\frac{18}{36} - \frac{40}{60} + \frac{12}{24} \\ \frac{3}{6}- \frac{4}{6} + \frac{3}{6} = 2/6 = 1/3$$
