How do you simplify 8a plus 4b plus 4a plus 3b?

To simplify the expression (8a + 4b + 4a + 3b), first combine like terms. Add the coefficients of (a): (8a + 4a = 12a). Then, add the coefficients of (b): (4b + 3b = 7b). Thus, the simplified expression is (12a + 7b).