Explain the answer and how to get the answer?
50 people each did one activity at a sports centre.
some of the people went swimming.
some of the people played squash.
the rest of the people used the gym.
21 of the people were female.
6 of the 8 people who played squash were male.
18 of the people used the gym.
9 males went swimming.
work out the number of females who used the gym.

Let us imagine that the number of automobile accidents in a certain region are related to the regional number of registered automobiles in tens of thousands (b1), alcoholic beverage sales in $10,000 (b2), and decrease in the price of gasoline in cents (b3). furthermore, imagine that the regression formula has been calculated as: y = a + b1x1 + b2x2 + b3x3 where y = the number of automobile accidents, a = 7.5, b1 = 3.5, b2 = 4.5, and b3 = 2.5 calculate the expected number of automobile accidents for a football weekend if the region has 25,000 registered vehicles, $75,000 worth of beer is sold, and a gas war causes a 10 cent drop in a gallon of gas.