Answer:
3*21+3*6 = 81
Explanation:
3(21+6) is basically 3 times 21 plus 3 times 6. You are distributing the 3 to the 21, and then also to the 6. Once you distribute the 3, you get 3*21+3*6. First, multiply 3 by 21 to get 63. Then, multiply 3 by 6 to get 18. Follow the equation and add them together to get your answer of 81.
You could also do it a different way and instead of doing 3*21+3*6, you could do the original equation, and do 3(21+6). 21+6=27 You then have 3(27). 3 times 27 is 81. You get the same answer, you could just do it a different way.