What is the sum of a 7 term geometric series if the first term is 6 the last term is 24576 and the common ratio is -4

I’m stuck on this i don’t understand.

Gregory draws a scale drawing of his room. the scale that he uses is 1 cm : 4 ft. on his drawing, the room is 3 centimeters long. which equation can be used to find the actual length of gregory's room?

Kendra had twice as much money as kareem. kendra later spent $8 and kareem earned $6. by then, the two had the same amount of money. how much money did each have originally?