How and what are they :/ plz help

Determine which expressions represent real numbers and which expressions represent complex number. asaaap! plis!

You have 138.72 in your saving account u take out 45.23 and 18.00 you deposit 75.85 into your account

What is the volume of the cone to the nearest cubic millimeter? (use π  = 3.14) a) 46 mm3 b) 128 mm3 c) 183 mm3 d) 275 mm3 diameter = 5 mm height = 7 mm how do you do this problem step by step?