Question 672301
let x ml of 40 % acid should be added to (75-x)ml 100% pure acid to make 75 ml of 65 % acid
so (40x/100)+(75-x)*100/100=65*75/100
or 40x+100(75-x)=65*75
or 40x-100x=65*75-100*75=75(65-100)=-75*35
or -60x=-75*35
or x=75*35/60=43.75 ml ans