How do you know if vertices make a right triangle?

Can someone me out here and the tell me the greatest common factor

How many 3/8s are in 6 plz someone tell me now

Ican interpret and represent the remainder in division calculations sensibly for the context (eg 27.4 in calculating average height in cm: $27.44 if it represents an amount of money) solve the following problems. 15) the wildlife park charges $25.50 dollars per person to enter their park if the park made $15096 dollars today, how many people entered the park? 16) ms adams plus 2,230 other keen runners ran a marathon: between them they ran 94817.5km. how many km did each competitor run?