ax + bx + 3a + 3b / x + 3

To simplify the expression, we can combine like terms in the numerator:

(ax + bx + 3a + 3b) / (x + 3)

Combine like terms in the numerator:

(ax + bx + 3a + 3b) = x(a + b) + 3(a + b) = (x + 3)(a + b)

So the simplified expression is:

(x + 3)(a + b) / (x + 3)

Now we can cancel out the common factor of (x + 3) in the numerator and denominator:

(a + b)

3(a + b)