Final answer:
In the equation y = 3x + 12, y represents the output and x represents the input. By substituting the value of x into the equation, we can find the value of y. Therefore, when x = 2, y equals 18.
Step-by-step explanation:
In the equation y = 3x + 12, y represents the value of the dependent variable (usually the output) and x represents the value of the independent variable (usually the input). To find the value of y when x is given, substitute the value of x into the equation and simplify. For example, if x = 2:
y = 3(2) + 12
y = 6 + 12
y = 18