Answer:
10. 12a
11. 24x
12. 4x+1
Step-by-step explanation:
For answer 10 you are combining like terms, there is only one term (a) so you add the numbers and add whatever letter is with the numbers. So it’s 12a
For answer 11 it’s talking about perimeter so you add all together and you get 24 then you add the (x) after the 24 because it was saying 6x and you just added 6 four times with the variable at the end. So it is 24x
Sorry if this doesn’t make sense but I am not very good at explaining things
