Final answer:
The relationship between the number of times Franklin uses his card to ride the bus and the remaining balance on his card is a linear function, represented by the equation y = 10 - 2x.
Step-by-step explanation:
The relationship between x, the number of times Franklin uses his card to ride the bus, and y, the number of dollars that are left on his card is a linear function. Each time Franklin rides the bus, $2 is deducted from his card. If we let Franklin's initial amount of $10 be represented by y when x is 0 (no trips taken), we can see that every bus ride (increase in x by 1) decreases the total amount (y) by $2. This creates a straight-line graph, where y decreases at a constant rate as x increases. Therefore, the equation that represents this relationship is y = 10 - 2x, which is the standard form of a linear function where the slope is -2 and the y-intercept is 10.