Expert: Ahmed Salami - 9/28/2010

Question
Hi my question in involves all letters. I'm trying to solve for x and y.
Here is my equation:
ax+by=c
mx-ny=d

Answer
Hi Gill,
ax + by = c
mx - ny = d
multiplying the first equation by n and the second by b, we have
anx + bny = nc
bmx - bny = bd
adding the equations,
anx + bmx = nc + bd
x(an + bm) = nc + bd
x = (nc + bd)/(an + bm)
returning to the original equations and multiplying the first equation by m and the second by a, we have
amx + bmy = mc
amx - any = ad
subtracting
bmy + any = mc - ad
y(bm + an) = mc - ad
y = (mc - ad)/(bm + an)

Regards