Question

How to solve this problem that don't nor know

Answer 1

Well, for number 23 you have to figure out what n is. In order to do that you have to multiply different numbers to figure out the number for n. I hope this helps and have a wonderful day.

Answer 2

21) - 4 + 7 (1 - 3m) = - 4 + 7 - 21m = 3 - 21m
23) - 2n - (9 - 10n) = - 2n - 9 + 10n = 8n - 9