1) a/4=b/5=c/9=k⇒ a=4k⇒b=5k⇒c=9k
a+b+c=3240⇒4k+5k+9k=3240⇒18k=3240⇒k=3240÷18⇒k=180
a=180×4⇒a=720
b=180×5⇒b=900
c=180×9⇒c=1620
ver;
a+b+c=3240⇒720+900+1620=3240.
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2)
200 grau.......175 faina
x.................525
x=525×200÷175
x=105 000÷175
x=600 kg grau
200 grau.......175 faina
100 ..............x
x=100×175÷200
x=17500÷200
x=87.5 kg faina....................