Answer
$$12a^2 - 13ab - 35b^2$$
Work Step by Step
We use distributive property to multiply each term in the first binomial by each term in the second binomial:
$$3a(4a) - 7b(4a) + 5b(3a) - 7b(5b)$$
Multiply to simplify:
$$12a^2 - 28ab + 15ab - 35b^2$$
Group like terms:
$$12a^2 + (-28ab + 15ab) - 35b^2$$
Combine like terms:
$$12a^2 - 13ab - 35b^2$$
