Most of those are correct but the ones that are not are, (15+8 divided by 4-6) as division comes first. 6x3-8 as multiplication comes before subtraction. And 2/3+4x2, multiplication comes before addition. So change those couple up and you got it.
Answer: See the pictures
Step-by-step explanation:
Hope I helped!
Sorry it took so long btw
The average speed would be 600 km/hr.
Step-by-step explanation:
Let the original speed be 'x'
Let the decreased speed be 'x-200'
Distance = 600 km
Time increased by 30 minutes
According to question, it becomes,

So, The average speed would be 600 km/hr.