Final answer:
The original value of the card was $9, found by calculating the y-intercept of the equation representing the value of the card over time.
Step-by-step explanation:
The original value of the baseball card when Robert first purchased it can be found by determining the y-intercept of the equation y = 9 + 3x, which represents the value of the card when x (the number of years owned) is 0. To find this, we simply plug 0 in for x and solve for y, which gives us y = 9. This means that the card's value was $9 when Robert originally purchased it.