What the answers to estimate 4.23-2.51

Which of these is and example of a literal equation? a) 6+30=6^2 b)3x-4y c)12=9+3x d)ax-by=k

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.

Adie is rolled, what is the probability of getting an even number or a 3? write the solution too