Adjacent angles are angles that are side by side (right next to each other). They share a side. #7 and 11 are pairs of adjacent angles.
Vertical angles are angles that are directly across from each other. They are the same angle. #8 and 9 are vertical angles.
#10 and 12 do not fit either of these descriptions so they are neither.
The top 4 firms have (23 +22 +18 +12)% = 75% of the market.
The 4-firm concentration ratio is 0.75 or 75%.
50-(30.8+4.9)=14.3 kg.
You start with 50 then you need to subtract 30.8 and 4.9 from it. So you add them together and get 35.7. Then you subract 25.9 from 50 and get 14.3 kg.
How to solve with elimination: with the equations on the top, add the number on top and bottom if they share a variable such as x. do the rest for all of the numbers.
