Can someone please help! I don’t understand this

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?

What rule describes a dilation with a scale factor of 4 and the center of dilation at the origin?

Write a ratio and a percent for the shaded area. it is 3x3 and 5x5 grid there is 6 shaded out of a. 6 over 25 , 30% b. 3 over 50 , 6% c.6 over 25 , 24% d. 3 over 10 , 30%