Explanation

The typical way to do this problem would be to assign variables and set up equations, using x to represent the number of classes Randolf took, 12x to represent the amount he paid, and 45x to represent the number of minutes he spent.

A quicker way might be to notice that with every class Randolf takes, the difference between the number of minutes he spends and the amount he pays increases by 33. If Randolf takes 1 class, then the number of minutes he spends is 33 greater than the number of dollars he pays. If he takes 2 classes, the number of minutes is 66 greater than the number of dollars, and so on. Since 132 = 4 × 33, Randolf must have taken 4 classes.

Hence option B is correct!