Answer:
18
It’s literally 72 divided by 4 which equals 18
        
             
        
        
        
3 : 3,6,9,12,15,18,21,24,27,30
4 : 4,8,12,16,20,24,28,32,36 
7: 7,14,21,28,35,42,49,56,63
9: 9,18,27,36,45,54,63,72,81
        
                    
             
        
        
        
Answer:
#16 = (0, -10)
#17 = (-18, -3)
Step-by-step explanation:
U wouldn't use the distance formula, you would need to use the Midpoint Formula, which is, M = (x1 + x2 / 2, y1 + y2 / 2). For #16, you plug in (4, -5) for M and 8 for x1 and 0 for y1, so the equation should look like this : (4, -5) = (8 + x2 / 2, 0 + y2 / 2). Then separate the equation to make it easier: 4 = 8 + x2 / 2 and the second equation : -5 = 0 + y2 / 2. So let's do the 1st equation, the first step would be to multiply the 2 to both sides. So the equation should look like this, 8 = 8 + x. Then subtract the 8 from both sides and you get 0 as your x. Now moving on to the 2nd equation, you multiply the 2 to both sides, and you get, -10 = 0 + y, as your equation, but since 0 won't affect it, -10 should be your y. Then just use these steps to solve #17, and your answer should be (-18, -3).