Can you please answer number one and two, I need an example on how to do this and I’m stuck on these two problems :(

Find the missing variable for a parallelogram: a = latex: 28in^2 28 i n 2 h = b = 6.3 in (1in=2.54cm)

Hello, i need compare km^2 and km. what's difference in this?

Study results indicate that the mean length of time people spend on a bus in a city is between 21.2 min and 24.5 min what is the study margin of the error?