The right equations are a+c=30 (total number of people) and 8a+c=100 (total amount of money). So answers B and D cannot be right.
a+c=30 can be rewritten as c=30-a and filled into the second one:
8a + 30-a = 100 => 7a = 70 => a=10
That leaves answer A as the right one.
There is a 75 percent chance the event will occur
Kepler was a student of Copernicus who went with observations he made instead of tradition.
To solve this simply divide 4 by 3 and use the long division and do the same for 11 and 9, then compare the values.
