The equation when multiplying binomials is a^2 + 2ab + b^2. Therefore when you use FOIL (First, Outer, Inner, Last), you will multiply a times a and a times -4, which gives you a^2 - 4a. Now you take the second term and do 7 times a and 7 times -4, which gives you 7a - 28. Combine them and you have a^2 - 4a + 7a - 28. Then combine the middle two terms and that gives you 3a. You will always have to combine like terms and it will always be the two middle terms. So your answer is a^2 + 3a - 28. Hope this helps. Please rate, leave a thanks, and mark a brainiest answer (Not necessarily mine). Thanks, it really helps! :D
