N/8 = 25/40

N/20=85/100

2/3=16/n

5/6=25/n

N/8 = 25/40

40n = 25 * 8

40n = 200

n = 200/40

n = 5

n/20 = 85/100

100n = 85 * 20

100n = 1700

n = 1700/100

n = 17

2/3 = 16/n

2n = 16 * 3

2n = 48

n = 48/2

n = 24

5/6 = 25/n

5n = 25 * 6

5n = 150

n = 150/5

n = 30