Answer
$$21x^2 - 23x - 20$$
Work Step by Step
To simplify this expression, we need to use FOIL to multiply the two binomials. We first multiply the first terms, then the outer terms, then the inner terms, and, finally, the last terms:
$$7x(3x) + (7x)(-5) + (4)(3x) + (4)(-5)$$
Multiply the terms to simplify:
$$21x^2 - 35x + 12x - 20$$
Group like terms:
$$21x^2 - 23x - 20$$
