1, Might not be precise
2, Can be hard to plot the graphs
3, If there are many solutions that will be really hard to plot sometimes.
This is just from the top of my head.
Answer: -30
Step-by-step explanation: -13 subtract 17 = -30
Answer:
m:
Step-by-step explanation:
Pick two points (0,5) and (3,4)
use the formula to find slope: 
Insert values: 
m:
:-)