To find the cost of a child ticket, we first note that the price of an adult ticket is $42.50. The cost of a child ticket is given as \( \frac{6}{10} \) of the price of an adult ticket.
Let's calculate the child ticket price:
\[ \text{Child ticket price} = \frac{6}{10} \times 42.50 \]
Calculating that step-by-step:
- Multiply the adult ticket price by \( \frac{6}{10} \):
\[ 42.50 \times \frac{6}{10} = 42.50 \times 0.6 \]
- Now perform the multiplication:
\[ 42.50 \times 0.6 = 25.50 \]
Thus, the cost of a child ticket is 25.50.