Answer:

Step-by-step explanation:
Given

Required
Determine an equivalent expression
Express 81 as 

Apply law of indices






Hence:

Answer: The correct option is D: Is alloyed with carbon and chromium to make stainless steel.
Explanation: Because of its physical characteristics, iron is a material that tends to oxidize easily. With the chromium alloy stainless steel is created, which for its quality can be used in the manufacture of structural steels.
Answer:
C) 80
Step-by-step explanation:
triangles always add up to 180 degrees, so 80+20=100 the missing angle is 80 degrees
Answer:
23.8
Step-by-step explanation:
2(5.7) + 2(6.2)
11.4 + 12.4
23.8