Xiaohua rides a bicycle, while Xiaoming rides a motorcycle from two places 80 kilometers apart. After meeting each other on the way, they continue to walk backward. Five hours after starting, they are 205 kilometers apart. Given that Xiaohua travels 15 kilometers per hour, how many kilometers does Xiaoming travel per hour? (solution of a series of equations)

Xiaohua rides a bicycle, while Xiaoming rides a motorcycle from two places 80 kilometers apart. After meeting each other on the way, they continue to walk backward. Five hours after starting, they are 205 kilometers apart. Given that Xiaohua travels 15 kilometers per hour, how many kilometers does Xiaoming travel per hour? (solution of a series of equations)

Let Xiaoming travel x kilometers per hour, 15 × 5 + 5x = 205 + 80, 75 + 5x-75 = 285-75, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 5x = 210, & nbsp; & nbsp; 5x △ 5 = 210 △ 5, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 42, answer: Xiaoming travel 42 kilometers per hour

For a project, team a and team B work together for 30 days to complete. Now team a works alone for 24 days, team B joins, and the two teams work together for another 12 days. At this time, team a is transferred away, and team B continues to work for 15 days to complete the project. How many days does it take team a to do the project alone?

1 △ [(1-12 + 1530) × (24-15)] = 1 △ [(1-910) × 9], = 1 △ [110 △ 9], = 1 △ 190, = 90 (days). Answer: it takes 90 days for team a to do this project alone

Barrel a oil is 18 kg more than barrel B oil. If 17 kg is poured from barrel B, the ratio of barrel B oil to barrel a oil is 4:9?

(18 + 17) / (1 − 49), = 35 ／ 59, = 35 × 95, = 63 (kg), 63-18 = 45 (kg), a: barrel a used to be 63 kg, barrel B used to be 45 kg