15а-b/12a-a-4b/9a

To simplify the given expression, we need to combine like terms and simplify the fractions.

First, let's simplify the fractions individually:

For the first fraction, we have: 15a - b

12a

For the second fraction, we have: -4b

9a

Next, let's find a common denominator for the fractions, which is 36a:

For the first fraction, we need to multiply the numerator and denominator by 3: (15a * 3) - (b * 3) = 45a - 3b

(12a * 3) = 36a

For the second fraction, we need to multiply the numerator and denominator by 4: (-4b * 4) = -16b

(9a * 4) = 36a

Now, our expression is simplified to: (45a - 3b) - (16b)

  36a

Combining like terms, we have: 45a - 3b - 16b

36a

Simplifying further: 45a - 19b

36a

So, the simplified form of the expression is (45a - 19b)/(36a).