Answer:
21x-28
Step-by-step explanation:
the distributive property states that a(bx+c) is equal to abx+ac. in this expression, a is 7, b is 3, and c is negative 4. ab is 7*3, which is 21, so abx is 21x. ac is 7*-4, which is -28. combining these two results in 21x-28.
