Support vector machines

Given a weight vector $w = [2, -1]$ and bias term $b = 4$, what is the equation of the decision hyperplane in a binary classification problem using this SVM model?

Please enter your answer in the following format: w_1x_1 + w_2x_2 + b = 0

For example, 2x_1 + 3x_2 + 2 = 0