<u>Part a)</u>
Given the expression

Apply exponent rule: 
∵ 
Rewrite 81 as 3 · 27
Rewrite 54 as 2 · 27

Factor out the common term: 27m³n
Therefore,

<u>Part B)</u>
Given the expression

Apply exponent rule: 

Rewrite as

Factor out common term 5y²x²z

Therefore,

15% of 425
(15/100) * 425
(3/20) * 425
(3/4) * 85
255 / 4
63.75
Answer:2.63%
Step-by-step explanation:9.65-9.25=0.40
0.40÷9.25×100=
2.63℅ rounded off to 2decimal places.