To solve the problem, we want to express the cost of one adult ticket and one child ticket and set up an equation based on the given information.
Let \( A \) be the cost of one adult ticket. Then the cost of one child ticket would be \( A - 3 \).
We know that:
- The total cost for 3 adult tickets and 3 child tickets is $75.
This can be expressed as: \[ 3A + 3(A - 3) = 75 \]
Now, simplifying the left-hand side: \[ 3A + 3A - 9 = 75 \] \[ 6A - 9 = 75 \]
To isolate \( A \), we can first add 9 to both sides, which leads us to: \[ 6A = 75 + 9 \] \[ 6A = 84 \]
Now, dividing both sides by 6 gives: \[ A = 14 \]
Thus, the cost of an adult ticket would be $14 and the cost of a child ticket would be \( 14 - 3 = 11 \).
Looking at the options provided, the first step we would logically take to solve this equation correctly is: A: add 3 to 75 to account for the cost of the child tickets calculated from the adjusted equation.
So the correct answer is: A add 3 to 75.