Answer:
Step-by-step explanation:

the answer is c.
you have to multiply by -3 on both sides to get c on its own.
therefore, c is greater than or equal to -9.
in a, c is less than or equal to 9 so thats not the answer.
In b, c is greater than or equal to 9 but it has to be -9.
in d, c is less than or equal to -9.
the answer is c
Option c is your answer 3xy + 7x4
Firstly, you would subtract 7 from both sides, leaving you with 3m=21. You would then divide by three in order to be left with total value of m. 3m divided by 3 is m. 21 divided by 3 is 7. Therefore m=7 :)