12 points, help plz.

Here is a number machine.
Input x5
Output -3

a) work out the output when the input is 8

b) work out the input when the output is 42

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

In the sixth grade 13 out of 20 students have a dog if there are 152 sixth grade students how many of them have a dog

Here are the 30 best lifetime baseball batting averages of all time, arranged in order from lowest to highest: 0.319, 0.329, 0.330, 0.331, 0.331, 0.333, 0.333, 0.333, 0.334, 0.334, 0.334, 0.336, 0.337, 0.338, 0.338, 0.338, 0.340, 0.340, 0.341, 0.341, 0.342, 0.342, 0.342, 0.344, 0.344, 0.345, 0.346, 0.349, 0.358, 0.366 if you were to build a histogram of these data, which of the following would be the best choice of classes?