Marbles Problem

Lucas has three times as many marbles as his friend Nathan. If Nathan has 12 marbles, how many marbles does Lucas have?

Let Nathan's number of marbles be represented by $n$. According to the problem, Lucas' number of marbles, $L$, can be represented as:

$$L = 3n$$

Substituting Nathan's number of marbles:

$$L = 3 imes 12$$