If (a + b) : (b + c) : (c + a) = 3 : 6 : 5 and 2a + 3b = 40, then b i…

a + b = 3R, b + c = 6R, c + a =5R

Adding all of above, we get:

2(a + b + c) = 14R

(a + b + c) = 7R      ...............(i)

b + c = 6R   ...........(ii)

(i) - (ii)

a = 1R, similarly b = 2R,  c = 4R

Now,

⇒  2a +  3b = 40

⇒  (2 × 1R) +  (3 × 2R) = 40

⇒  2R  + 6R = 40

⇒  8R = 40

⇒  1R = 5

 Here,

b  = 2R = 2 × 5 = 10