Answer:
Because there are many different ways to teach introductory astronomy, we have made the text as flexible as we could. Math examples are shown in separate sections throughout, so that you can leave out the math or require it as you deem best. Each section of a chapter treats a different aspect of the topic being covered; a number of sections could be omitted in shorter overview courses and can be included where you need more depth. And, as we have already discussed, you can customize the book in a variety of ways that have never been possible in traditional textbooks.
Step-by-step explanation:
This book is written to help students understand the big picture rather than get lost in random factoids to memorize. The language is accessible and inviting. Helpful diagrams and summary tables review and encapsulate the ideas being covered. Each chapter contains interactive group activities you can assign to help students work in teams and pool their knowledge.
Answer: 
hours
Step-by-step explanation:
Let x be the time ( in hours ) you feel good and y be the time ( in hours ) that you get tired.
As per given , we have
x+y= 8
Since : 
So , we have
20x+12y=122
According to the given question , we have the following system of equations ,
Multiply 12 on both sides of equation (1) , we get
Eliminate equation (3) from (2) , we get
Hence, you felt hours good.
Answer:
The second tank.
Step-by-step explanation:
Since both filling up at the same rate, all you would have to do is multiply the gallons.
4/5 multiplying top and bottom by 8 is 32/40
7/8 multiplying top and bottom by 5 is 35/40
