The intersection of two planes is a line. That's not necessarily the definition of a line, but that's probably what they're looking for.
Answer: line
Add half a tenth.
.. 4.9675 +0.05 = 5.0175
Throw away all the digits to the right of the tenths digit.
.. 5.0
Your rounded number is 5.0
is there a picture i can use to help out?
