Answer Happy

Please solve each part of the question. I will upvote.
1) A water pipe at 13 degrees passes through a basement in which the air is at 21 degrees. The atmospheric pressure is 100kPa. Assume that the outer part of the pipe is 13 degrees. a) Maximum allowable value of dew point temperature if no condensation is to occur. b) Maximum allowable relative humidity the air can have before the conden- sation occurs on the pipe's outer surface.