i just did some long algebra. i did use the calc a bit though (to speed things up), idk if you can.
im a noob at maths though, so i'll just say i got:
b = -1
a = -4/19
c = 17/76
pretty sure i got it wrong though.
so if you know the answers and see this wrong, do NOT do what i did which was:
find a in terms of b.
use a in terms of b to find b.
sub b in 'a in terms of b' to find a.
sub these into one equation.
yeah. sorry if that was long.
*Edit* mega lag whilst trying to edit >__> yeah i checked this and my answers are WRONG. they only work for the second equation and not the first ¬¬ sorry OP.