Bill and Tom together have 112 baseball cards. Bill has 28 more than tom. How many does each boy have? Define a variable, write an equation, and solve the problem
(Unit: Solving Equations: Variables on Both Sides)

Let Cards with Tom be x

Therefore ,

Cards with Bill=x+28

No. of cards in total=112

x+x+28=112

2x=84

x=42.

Therefore,

Cards with Tom=42

Cards with Tom=42Cards with Bill=70

(a)

Q1, the first quartile, 25th percentile, is greater than or equal to 1/4 of the points.  It's in the first bar so we can estimate Q1=5.   In reality the bar includes values from 0 to 9 or 10  (not clear which) and has around 37% of the points so we might estimate Q1 a bit higher as it's 2/3 of the points, say Q1=7.

The median is bigger than half the points.  First bar is 37%, next is 22%, so its about halfway in the second bar, median=15

Third bar is 11%, so 70% so far.  Four bar is 5%, so we're at the right end of the fourth bar for Q3, the third quartile, 75th percentile, say Q3=40

b

When the data is heavily skewed left like it is here, the median tends to be lower than the mean.  The 5% of the data from 80 to 120 averages around 100 so adds 5 to the mean, and 8% of the data from the 60 to 80 adds another 5.6, 15% of the data from 40 to 60 adds about 7.5, plus the rest, so the mean is gonna be way bigger than the median of around 15.