a) A = 3^11.11 + 3^11.21 / 3^9.2^5

To simplify this expression, we can use the rules of exponents.

First, let's simplify the numerator: 3^11.11

Since the exponent is a decimal, we can rewrite it as a fraction: 11.11 = 11 + 1/10

So, 3^11.11 = 3^11 * 3^(1/10)

Now, let's simplify the denominator: 3^9.2^5

We can rewrite it as: (3^9) * (2^5)

Now, let's substitute these values back into the original expression:

A = (3^11 * 3^(1/10)) + (3^11.21 / (3^9 * 2^5))

Next, let's simplify the terms separately:

3^11 * 3^(1/10) = 3^(11 + 1/10) = 3^(110/10 + 1/10) = 3^(111/10)

3^11.21 = 3^11 * 3^(0.21) = 3^11 * 3^(21/100)

Now, let's substitute these simplified terms back into the expression:

A = 3^(111/10) + (3^11 * 3^(21/100)) / (3^9 * 2^5)

Now, let's simplify the denominator further:

3^9 * 2^5 = (3^3)^3 * (2^5) = 27^3 * 32

Finally, let's substitute this simplified denominator back into the expression:

A = 3^(111/10) + (3^11 * 3^(21/100)) / (27^3 * 32)

b) B = 5.4^15.9^9 - 4.3^20.8^9 / 5.2^9.6^19 - 7.2^29.27^6

To simplify this expression, we can use the rules of exponents.

First, let's simplify the numerator: 5.4^15.9^9

Since the exponents are decimals, we can rewrite them as fractions: 15.9 = 15 + 9/10

So, 5.4^15.9^9 = 5.4^15 * 9^9 * 5.4^(9/10)

Now, let's simplify the denominator: 4.3^20.8^9

We can rewrite it as: (4.3^20) * (8^9)

Now, let's substitute these values back into the original expression:

B = (5.4^15 * 9^9 * 5.4^(9/10)) - (4.3^20 * 8^9) / (5.2^9 * 6^19) - (7.2^29 * 27^6)

Next, let's simplify the terms separately:

5.4^15 * 9^9 * 5.4^(9/10) = 5.4^15 * 9^9 * 5.4^(9/10)

4.3^20 * 8^9 = 4.3^20 * 2^27

5.2^9 * 6^19 = 5.2^9 * 6^19

7.2^29 * 27^6 = 7.2^29 * 3^18

Now, let's substitute these simplified terms back into the expression:

B = (5.4^15 * 9^9 * 5.4^(9/10)) - (4.3^20 * 2^27) / (5.2^9 * 6^19) - (7.2^29 * 3^18)

Note: The expression is quite complex and may require further simplification depending on the specific values of the exponents.