Question 1197437
w, amount of 60%
400-w, amount of 40%


{{{60w+40(400-w)=51*400}}}
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{{{60w-40w+40*400=51*400}}}
{{{(60-40)w=51*400-40*400}}}

{{{w=(51*400-40*400)/(60-40)}}}

{{{highlight(w=400((51-40)/(60-40)))}}}------some people know a shortcut to reach this.
Compute w.