I think this is how you do it...hope it helps
Step-by-step explanation:
x-3>7 =>
x>10
hope this helps
So you know the whole line is XZ which is 83.Then you find out it is in two parts so that is XY and YZ which are 11 and 4c. You can make the equation:
11+4c=83
4c=72
c=18
c=18 and YZ=72