slight variation

students are advised to think about the coefficients before leaping in to standard solution techniques

question 1 could have solution (3, 2) or (1, 5) or (5, -1) or... ?

question 6 could have solution (3, 2) or (2, 7) or (1, 12) or...?

how do you know when two simultaneous equations have an infinite number of solutions?

why do small variations produce quite different solutions?