To simplify the expression 5x + 3y - 2x + 4y, we need to combine like terms. To do this, we need to look for terms that have the same variables and coefficients. In this expression, the terms 5x and -2x both have the variable x and can be combined. Similarly, the terms 3y and 4y both have the variable y and can be combined.
To combine the like terms, we add the coefficients and keep the variable the same. So, to combine 5x and -2x, we have:
5x + (-2x) = (5 + (-2))x = 3x
To combine 3y and 4y, we have:
3y + 4y = (3 + 4)y = 7y
Now that we have combined the like terms, we can simplify the expression to:
3x + 7y
Therefore, the simplified form of the expression 5x + 3y - 2x + 4y is 3x + 7y.