To determine the total cost [tex]\( (a) \)[/tex] of buying one small toy car and one large toy car, let's break down the steps involved in the calculation.
1. Identify the cost of each type of car:
- The cost of a small toy car is \[tex]$3.
2. Determine the cost of the large toy car:
- The large toy car costs 5 times as much as the small toy car.
- Therefore, the cost of the large toy car is \( 5 \times \$[/tex]3 = \[tex]$15 \).
3. Calculate the total cost of buying both cars:
- The total cost will be the sum of the cost of the small toy car and the cost of the large toy car.
- In other words, \( a = \$[/tex]3 + \[tex]$15 \).
Putting these steps together, the equation that can be used to find the total cost \( (a) \) is:
\[ \$[/tex]3 + (5 \times \[tex]$3) = a \]
Thus, the correct equation from the provided options is:
\[
\$[/tex]3 + (5 \times \[tex]$3) = a
\]
By solving this equation, we get:
\[ a = \$[/tex]3 + \[tex]$15 = \$[/tex]18 \]
Therefore, Aaron will spend a total of \$18 to buy one small toy car and one large toy car.