Hunter x Hunter rp

IM KILLUA

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

Phillip had some bricks. he stacked them in 6 equal piles. which expression shows the number of bricks phillip put in each pile? let the variable m stand for the unknown number of bricks. m + 6 m÷6    m−6    6m

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?