Answer:
they are adding by 7 because 6 +7=13
You will read for 45 minutes if your brother reads for 15 minutes.
<em><u>Explanation</u></em>
You decide to read 30 minutes longer than your brother reads.
If your brother reads
number of minutes, then 30 minutes longer than
minutes means
minutes.
As the number of minutes you read is
, so the equation will be: 
When your brother reads for 15 minutes, then we will just <u>plug
into the above equation</u>. So.....

So, you will read for 45 minutes if your brother reads for 15 minutes.
The answer is 3.4 because 30 can’t be divided equally into 9, reason being that 9 x 30 = 270 which doesn’t make sense, so you have to divide 30 equally into 9 parts then turn it into a ratio.
I am pretty sure the answer is 2,520.