let age of one brother =2x
let age of second brother=3x
ratio of ages = 2x/3x
in eight years
age of first brother =2x+8
age of second brother= 3x+8
ratio of ages after 8 years =3/4

cross multiplying :
4(2x+8) = 3( 3x+8)
8x +32 = 9x+ 24
x=8
age of older brother= 3x =3*8 =24 years