follow order of operations:
3+16/4 = 3+4 = 7
+7 would be the answer i believe
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
3^-4 = 1/3^4 = 1/81
hope it helps!
Well what you would have to do is look for numbers that are easy to divide. For example, lets try 9000/10, and so the answer would be 900 and so if you divide the actually numbers, you could compare them, and see if 900 would be a reasonable.