The graph shows a proportional relationship between the number of kilometers traveled by a bicycle (y) and the number of minutes (x). a graph with a line running through coordinates (0,0) and coordinates (40,12) what is the unit rate, expressed in kilometers per minute? 0.30 km/min 0.33 km/min 3.10 km/min 3.33 km/min

The rate is 0.30 km/min. The rate in linear functions, which must be assumed with only two given points can be traced to calculating the slope (m) of the line or rate.  
m= (y2-y1) / (x2-x1)  
with our two given points (x,y) we fill out the equation as:  
M= (12 - 0) / (40 - 0) or M = 12/40 = 0.3  
keeping our units intact 12 km / 40 min so the answer is 0.3 km/min

To find the unit rate, expressed in kilometers per minute you must find the equation of the line, which in this case will be given by:
 y = 0.3x
 The slope of the line represents the unit rate.
 Therefore, the answer is
 0.30 km / min