151000x100 31012x 0520x200Solutioni 15 1000 x 100 ie 1510

15:1000::x:100 3:10::12:x 0.5:20::x:200

i) 15 : 1000 :: x : 100

i.e., 15/1000 = x/100

i.e., x/100 = 15/1000

i.e., x = (15*100)/1000

i.e., x = 1500/1000

i.e., x = 3/2

i.e., x = 1.5

ii) 3 : 10 :: 12 : x

i.e., 3/10 = 12/x

i.e., 3*x = 12*10 [by cross multiplication]

i.e., x = (12*10)/3

i.e., x = 120/3

i.e., x = 40

iii) 0.5 : 20 :: x : 200

i.e., 0.5/20 = x/200

i.e., x/200 = 0.5/20

i.e., x = (0.5*200)/20

i.e., x = 100/20

i.e., x = 5.