Answer:

Step-by-step explanation:
Given

Required
Determine an equivalent expression
Express 81 as 

Apply law of indices






Hence:

Find r :
C=2πr
280=2(3.14)r
r=280/2(3.14)
r=44.6cm
find area :
A=πr²
A=3.14(44.6)²
A=6246 cm²
Answer : 4)6,246
Answer:
Step-by-step explanation:
It's 12x. you just combine both numbers
Remember that X will always be one up or down depending on if there is a - or not (if it is just an x) and one over! Hope this helps