The ratio of football cards to baseball cards is 7:2 and the ratio of baseball cards to basketball cards is 7:1. To solve this problem, we need the baseball card side of each ratio to be equal so we need to rewrite the ratios in terms of a common number of baseball cards. (Think of this like finding the common denominator when adding fractions.) The ratio of football to baseball cards can also be written as 49:14 and the ratio of baseball cards to basketball cards as 14:2. So, the ratio of football cards to basketball cards is football:baseball, baseball:basketball or 49:14, 14:2 which reduces to 49:2.

A ratio of 3:1 means that there are 3 home fans for every one visiting fan. So, of every 4 fans, 3 are home fans and \( \frac{3}{4} \) of every fan in the stadium is a home fan:

40,000 fans x \( \frac{3}{4} \) = \( \frac{120000}{4} \) = 30,000 fans.

66% of the water consumption is industrial use and 31% is personal use so (66% - 31%) = 35% more water is used for industrial purposes. 15,000 gallons are consumed daily so industry consumes \( \frac{35}{100} \) x 15,000 gallons = 5,250 gallons.

To multiply fractions, multiply the numerators together and then multiply the denominators together:

\( \frac{3}{5} \) x \( \frac{4}{7} \) = \( \frac{3 x 4}{5 x 7} \) = \( \frac{12}{35} \) = \(\frac{12}{35}\)

Use PEMDAS (Parentheses, Exponents, Multipy/Divide, Add/Subtract):

3 + (5 + 2) ÷ 2 x 5 - 2²
P: 3 + (7) ÷ 2 x 5 - 2²
E: 3 + 7 ÷ 2 x 5 - 4
MD: 3 + \( \frac{7}{2} \) x 5 - 4
MD: 3 + \( \frac{35}{2} \) - 4
AS: \( \frac{6}{2} \) + \( \frac{35}{2} \) - 4
AS: \( \frac{41}{2} \) - 4
AS: \( \frac{41 - 8}{2} \)
\( \frac{33}{2} \)
16\(\frac{1}{2}\)