Question 601741
<pre>

{{{system(Px+Qy=R,Sx+Ty=U)}}}

is solved by calculating these three determinants:

{{{D}}} = {{{abs(matrix(2,2,P,Q,S,T))}}} = {{{PT-QS}}}

{{{D[x]}}} = {{{abs(matrix(2,2,R,Q,U,T))}}} = {{{RT-QU}}}

{{{D[y]}}} = {{{abs(matrix(2,2,P,R,S,U))}}} = {{{PU-RS}}}

Then

{{{x}}} = {{{D[x]/D}}}

{{{y}}} = {{{D[y]/D}}}

Your system

{{{system(2x+4y=16,3x-5y=-9)}}}

has P=2, Q=4, R=16, S=3, T=-5, U=-9

Substitute those into the above and you will get:

x = 2, y = 3

Edwin</pre>