We can start solving this problem by using a system of equations. Let x be the selling price of a card and y be the selling price of a photo frame.
From the information given, we know that on the first day:
3x + 9y = 75 (1)
And on the second day:
8x + 5y = 67 (2)
Now we have two equations with two variables. To find the value of x and y, we can use either substitution or elimination method.
One possible way to solve for x and y is to use substitution method:
Solve equation (1) for x in terms of y:
x = (75 - 9y) / 3
Substitute this expression into equation (2) to eliminate x:
8((75 - 9y) / 3) + 5y = 67
Solving this equation for y:
y = 3
Now we can substitute this value of y back into equation (1) or (2) to find the value of x:
3x + 9(3) = 75
3x = 48
x = 16
So the selling price of a card is $16 and the selling price of a photo frame is $3.