ratios

if u learn only ratios topic then u can do 40% of paper as in each and every topic ratios are used


1) if a:b=2:3 &b:c=3:4 then find a:b:c ?

short cut :   a:b        2 : 3
                       b:c          3 : 4


 a:b:c = 2*3 : 3*3 : 3*4
           = 6: 9: 12   = 2 : 3 : 4

2) if a:b=2:3,b:c=4:5,c:d=3:4 then find a:b:c

short cut