Question 1031756
Let {{{ r }}} = number of red beads
Let {{{ b }}} = number of black beads
{{{ 1*r + .5*b = 20 }}} ( standard form )
{{{ r = -.5b + 20 }}} ( slope intercept form )
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Here's the plot of {{{ r = f(b) }}}
{{{ graph( 400, 400, -4, 45, -3, 25, -.5x + 20 ) }}}