10 saci de grau a cate 500hg=50kg=> 500kg grau
5 saci cu porumb a cate 70 kg fiecare=> 350kg porumb
6 saci orez=6x
1sac orez=x
1t si 210kg=1210kg
500+350+6x=1210=> 6x=1210-850=360=>x= 60kg[un sac orez]
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