Question

1.Afla nr a ,b,c stiind ca sunt direct proportionale cu 4 ,5 , 9 si suma lor este 3240.



2.Din 200 kg de grau sunt 175 kg faina. Din 525 cata faina se obtine din 200 kg grau.

VA ROG!

Answer 1

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.
----------------------------------------------------
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....................