Final answer:
To expand the expression 3(4x + 5y) using the distributive method, multiply each term inside the parentheses by 3 to get 12x + 15y.
Step-by-step explanation:
To expand the expression 3(4x + 5y) using the distributive method, we need to multiply each term inside the parentheses by 3. This can be done by multiplying 3 with 4x and 3 with 5y separately.
So, 3(4x + 5y) = 3 * 4x + 3 * 5y = 12x + 15y.