Answer:4.5xStep-by-step explanation:To solve 1.5x + 3x:Identify like terms: Both terms, 1.5x and 3x, have the variable x raised to the same power (which is 1). This means they are like terms and can be combined. Add the coefficients: The coefficients are the numerical parts of the terms, which are 1.5 and 3. 1.5 + 3 = 4.5Combine with the variable: Keep the common variable x.Therefore, 1.5x + 3x = 4.5x.