What's the standard equation of the circle with the general equation x2 + y2 + 4x - 2y - 20 = 0

Is the open sentence 5x-2=3x+2 true when x=2? justify your answer.

An air conditioning system can circulate 350 cubic feet of air per minute. how many cubic yards of air can it circulate per minute?

What is the least common multiple for 6 and 8? what is the least common multiple for 4 and 12 ? what is the least common multiple for 11 and 12? what is the least common multiple for 3 and 6?