Answer:
It costs 20 dollars for adults to enter the science center and 13 dollars for children to enter the science center.
Explanation:
The variable a represents adults and when a variable and a number are put next to each other it is the same as multiplying. Because we know this we can assume that 20 dollars is the cost of an adult entering the science center. We can do the same for the variable c which represents children, the cost of a child entering the science center must be 13.