Combine like terms: x + 3x + y + 5x.
The like terms in the expression x + 3x + y + 5x are x, 3x, and 5x. To combine them, we add the coefficients of the like terms:
x + 3x + y + 5x = (1 + 3 + 5)x + y = 9x + y
x + 3x + y + 5x = (1 + 3 + 5)x + y = 9x + y