a : b = 5 : 4, b : c = 6 : 5 এবং c : d = 2 : 7 হলে, (2a + 3d) ÷ (3d - 2a) = ?

a : b = 5 : 4 = 5 × 3 : 4 × 3 = 15 : 12
b : c = 6 : 5 = 6 × 2 : 5 × 2 = 12 : 10
c : d = 2 : 7 = 2 × 5 : 7 × 5 = 10 : 35
a : b : c : d = 15 : 12 : 10 : 35
a : d = 15 : 35 = 3 : 7
a/d = 3/7
d/a = 7/3
3d/2a = 21/6
(3d + 2a)/(3d - 2a) = (21 + 6)/(21 - 6)
(3d + 2a)/(3d - 2a) = = 27/15
(3d + 2a)/(3d - 2a) = 9/5