Q: A boy runs 1.5 km in 45 minutes. What is his speed in kilometers per hour?
A: Since 1 hour is equal to 60 minutes, then 45 minutes is equal to 45 / 60 = 0.75 hours. Then, the speed in kilometers per hour is 1.5 km / 0.75 hour = 2 kilometers per hour. The answer is 2.

Q: Ed and Jacob already had 2 shells in their shell collection. Then they went to the beach to collect even more. Ed found 7 limpet shells, 2 oyster shells, and 4 conch shells. Jacob found 2 more shells than Ed did. How many shells do the pair have altogether?
A: Ed found 7 shells + 2 shells + 4 shells = 13 shells at the beach. Jacob found 13 shells + 2 shells = 15 shells at the beach. In total Ed and Jacob have 2 shells + 13 shells + 15 shells = 30 shells. The answer is 30.

Q: John is 10 years old. His sister is twice his age. When he is 50 years old, how old will his sister be?
A:
His sister is 10 * 2 = 20 years old. Their age difference is 20 - 10 = 10 years. Therefore when he is 50 she will be 50 + 10 = 60 years old. The answer is 60.