Answer: Option A, $12.50
Step-by-step explanation: Jeff spent 3/8 of his money, which can be represented by the equation as follows:
1 - 3/8 = 5/8
where 1 represents 8/8, or $20, and 5/8 represents the remainder of Jeff's money.
To find how much money Jeff has left, we can multiply his initial investment by 5/8:
$20 × 5/8 = $100/8, or $12.50
Hence, Jeff has $12.50 leftover, which is represented by option A.