Either one at any given time could be equal to zero. So
x + 2 = 0
x = - 2
x - 18 = 0
x = 18
I've enclosed a graph of this so you can see that the answers I've given are the ones expected.
$21.50 - $4 = $17.50 If you start with $21.50, subtract the $4 entrance fee, you have $17.50 left to spend on rides. To figure out how many rides you can go on, divide $17.50 by $2.50. You can go on 7 rides. Here's the equation:
(21.5-4)/2.5=amount of rides
(21.5-4)/2.5= 7 rides
The mean means average. To find it, add together all of your values and divide by the number of addends. The median is the middle number of your data set when in order from least to greatest. The mode is the number that occurred the most often. The range is the difference between the highest and lowest values.