Answer: $8
Explanation:
Given : Jeff is buying apples and bananas from the farmer's market. He know that to find his total cost he will use the expression :
, where a stands for the number of apples he bought and b stands for the number of bananas he bought.
If he buys 4 apples and 6 bananas, the to find the total money spent put a= 4 and b= 6 in the above expression, we get

Therefore, the total amount money spent = $8