Please help with these matrices...

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.

The candy store is having a 30% off sale. emma is going to buy $7.50 worth of candy. how much will she pay after the discount

Answer this all of it i don’t know how to do it i wasn’t there because i was sick and it’s a nti today so i home not knowing what to do