Question 918656
{{{ 4x + 5y =5}}}....eq.1
{{{ 16x - 20y =10}}}...eq.2....simplify, divide by {{{4}}}
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{{{ 4x + 5y =5}}}....eq.1
{{{ 4x - 5y =10/4}}}...eq.2............add both eq.1 and eq.2
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{{{ 4x + 5y+4x - 5y =5+cross(10)5/cross(4)2}}}

{{{ 8x  =5+5/2}}}

{{{ 8x  =10/2+5/2}}}

{{{ 8x  =15/2}}}

{{{ x  =(15/2)/8}}}

{{{ x  =15/16}}}


{{{ 4x + 5y =5}}}....eq.1 substitute {{{x}}}

{{{ cross(4)(15/cross(16)4) + 5y =5}}}

{{{ (15/4) + 5y =5}}}

{{{   5y =5-(15/4)}}}

{{{   5y =20/4-15/4}}}

{{{   5y =5/4}}}

{{{   y =(cross(5)1/4)/cross(5)1}}}

{{{   y =1/4}}}



A)    The solution is_( {{{ 15/16}}},{{{ 1/4}}}) or as decimal ( {{{ 0.9}}},{{{ 0.25}}})


{{{ graph( 600, 600, -10, 10, -10, 10, 1-4x/5, 4x/5 -1/2) }}}