How do you find the greatest common factor of numbers?

Diana is painting statues. she has 7/8 of a liter of paint remaining. each statue requires 1/20 of a liter of paint. how many statues can she paint? yeah dad i added the cup to the door now will you stop emailing me while im doing my homework.(lmbo xd i just realized this wooow)

65 8 7 4 5 6 8 4 3 2 1 9 5 6 4 2 1 6 5 1 5 1 3 2 3 5 multiply the third number in the first row by the seventh number in the third row. add this result to the fifth number in the second row. add to this total ten times the fourth number in the third row. subtract the eighth number in the first row from the result.

15m is what percent of 60m; 3m; 30m; 1.5 km? the last one is km not m