A cyclist moves uphill at a speed of 10 km/h. When he reaches the top of the hill, he returns and passes the same track downhill at a speed of 40 km/h. What is the average speed of the cyclist in the whole journey given that the hill is 8km long?
A teddy bear costs 4 dollars and a doll cost 5 dollars. Teacher bought some toys including both teddy bears and dolls to give her students. She had to pay 36 dollars altogether. How many toys did she buy?
Anna has one square with side length 15cm and two identical right-angled triangles. She combines them to get a trapezium with area 345cm² as below. Find its perimeter.