Question 166561
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lets call the number of small sodas S
and the       number of large sodas L

so: {{{S+L=1000}}}
and:{{{.5S+.7L=580}}}

solve s in the first equation:{{{S=1000-L}}}
plug s's value into 2nd equation{{{.5(1000-L)+.7L=580}}}

solving for L  {{{500-.5L+.7L=580}}}----->{{{.2L=80}}}-->{{{L=400}}}

# of Large cups=400
# of small cups=1000-400=600