Answer 1

`(a - b)/(a + b) = 1/11`

11a - 11b = a = b

10a = 12b

`a/b = 12/10 = 6/5`

So let a = 6k and b = 5k

`(5a + 4b + 15)/(5a  - 4b + 3) = (5(6k) + 4(5k) + 15)/(5(6k) - 4(5k) + 3)`

`= (30k + 20k + 15)/(30k - 20k + 3)`

`= (50k + 15)/(10k + 3)`

`= (5(10k + 3))/(10k + 3)`

= 5

Hence (5a + 4b + 15):(5a - 4b + 3) = 5 : 1