What's the multiplicative inverse of -1/10?

Using graph paper, determine the line described by the given point and slope. click to show the correct graph below.(0, 0) and 2/3

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.

Based on the diagrams, what is the value of x?