What I did to solve this is finding the equation of the line using slope intercept form y is the cost of the ride which increases as you increase mileage or move along the X axis. My points are (2, 5.25) and (5,10.5)
y=mx+b
m=y2-y1/x2-x1
m=(10.5-5.25)/(5-2)
m=5.25/3=1.75 or 7/4
y=7/4x+b enter one point for the values of x and y to find b
10.5=(1.75X5) + b
10.5=8.75 + b
b=1.75
The equation of the line is y=7/4x+1.75 (I also double checked using the second point)
Then all you have to do is enter the mileage 3.8 for the value of X and solve for y
y=(7/4 X 3.8) + 1.75
y=6.65+1.75
y=8.4 The cab ride for the 3.8mile trip is $8.4
I hope this helps