Answer:
X=200
First your going to add all sides together. Once you finish you should get
50+55+90=195
after you got your answer your going to round to the tenths if it's higher than 5 your going to make it 200 but if it's lower than 5 than your going to make it 180.
So in our case because it's 195 we're going to turn it into a 200.
I hope this helps