Answer:
The equation representing the number of tickets sold is
.
Explanation:
Let the number of child tickets = x and the number of adult tickets = y.
We have,
Cost of 1 child ticket = $4. So, the cost of x child tickets = 4x dollars.
Cost of 1 adult ticket = $6. So, the cost of y adult tickets = 6x dollars.
Since, the total revenue from the tickets = $420.
We get the equation,
Cost of x child tickets + Cost of y adult tickets = Total revenue
i.e.

Hence, the equation representing the number of tickets sold is
.