10. Consider each scenario:

a) A high-speed passenger train in Europe completes an 800 km trip in 3 hours. The train travels the first 600 km at an average speed that was 100 km/h faster than the last 200 km of the trip. If x represents the average speed of the train on the second part of the trip, then an equation to represent this situation is:

600/x + 100 + 200/x = 3

Identify all restrictions on the variable x in this context.

b) Kailey is making earrings to sell at a local market. She spends $80 on supplies and decides to keep 4 pairs of earrings to give to her friends. Kailey sells the rest of the earrings she made for $175, making a profit of $9 per pair of earrings. If n represents the number of pairs of earrings Kailey made, then an equation that represents this information is:

9 = 175/n-4 - 80/n

Identify all restrictions on the variable n in this context. (2 marks)