System of equations and their graph
We have that the equation given by the Option A is:
y = 2x + 10
and the Option B equation is:
y = 3x
If we graph them, we will obtain the following figure:
C
The cost is the same when the two line intercept each other. Their interception at the tenth ride
When this happens the cost is $30
Answer: the total cost of both options is the same at the tenth ride
D
We have that the cheapest plan is always given by the line below.
Before the tenth ride:
the cheapest plan is the Plan B
After the tenth ride:
the cheapest plan is the Plan A
Since Plan A will be the cheaper in the future after Ride number 10, we can say that the cheapest plan is Plan B