The marginal cost is how much it costs to produce one item more. It cost 0$ to produce 0 bikes but if you make one, then it costs 80$. Hence the marginal cost for the first bike is 80$. For the fourth bike, we have that the 3 bikes cost 110$ and the 4 bikes cost 130$. Hence it costs 20$ dollars to produce one more bike (from 3rd to 4th) and hence the marginal cost is 20$. Similarly for the 6th bike, we compare the cost of producing 5 bikes to the cost of producing 6 bikes and we get that the marginal cost is 50$. Applying the same methodology, the marginal cost for the 7th bike is 60$.
The political parties attracted their candidates based on their beliefs and values. People who value less government involvement and lower taxes will attracted to the republican party while people who value more government involvement and higher taxes will attracted to democratic party.
For decades, scientists have supported the idea that facial expressions are universal. Many studies reveal that gestures like smiling are understood in the same way all around the world. And while it is true that different cultures have slight variations on the same expressions, it shoudln't be a problem to correctly interpret most emotions.
