Answer:
<em>We can't find a unique price for an apple and an orange.</em>
Step-by-step explanation:
Suppose, the price of an apple is
and the price of an orange is 
They need $10 for 4 apples and 4 oranges. So, the first equation will be.......

They also need $15 for 6 apples and 6 oranges. So, the second equation will be........

Dividing equation (1) by 2 on both sides : 
Dividing equation (2) by 3 on both sides : 
So, we can see that both equation (1) and (2) are actually same. That means, we will not get any unique solution for
and
here. Both
and
have <u>"infinitely many solutions"</u>.
Thus, we can't find a unique price for an apple and an orange.