To find the equation that represents Justin's age given that Kendra’s age is half the age of Justin and Kendra is 13 years old, we start with the relationship between their ages.
Since Kendra’s age is half of Justin’s age, we can express this relationship mathematically as:
- Kendra's age (13) = (1/2) * Justin's age (a).
Therefore, we can write the equation as:
\[ 13 = \frac{1}{2}a \]
To express this equation in a standard form, we can multiply both sides by 2:
\[ 2 \times 13 = a \] \[ 26 = a \]
So, the equation that correctly represents Justin's age is:
\[ \frac{1}{2}a = 13, \]
which means the correct response from the options provided is:
1/2a = 13.