The first option is correct.
You could do all the math to compare the final answers, but I looked at the part where you add. Using a standard algorithm, when going on to the next digit in the second number, you always add a 0 first. The rest of those options don't include a 0.
-c=p-r
If you were getting the negative C by itself you will want to move the R over on the opposite side. You do that by subtracting are to both sides the hours on the left cancel out leaving you with a negative C on the left side which equals P minus R on the right side
Start by looking at simplifying the smaller problems
anything to the power zero is 1

next apply the power of a power rule... multiply the powers

which becomes
18xy
You need to do 6*3=18
Then x*y= xy