Answer:

Step-by-step explanation:
Given

Required
Evaluate when n = 12
Substitute 12 for n in 

Simplify the fraction


For problems like this you can move the y's on the bottem up top by fliping the sign of the exponent (in this case 7 to -7) and MULTIPLYING it with EVERYTHING on top, then because of properties of multplication you can add the exponents to combine them into one term (in this case add 3 and -7 to get -4)

If any of this does not make sense let me know and ill try to clarify better
Answer: 40%
Step-by-step explanation: 100 ÷ 5 = 20 so 20 × 2 = 40