300g of 25% solution will contain `=(25xx300)/(100)`
`=75g` of solute.
400g of 40% solution will contain
`=(40xx400)/(100)=160g` of solute
`therefore` total mass of solute `=160+75=235g`
Total mass of solution `=300+400=700g`
Now, the percentage of solute in solution
`=(235)/(700)xx100=33*5%`
and, the percentage of water is solution
`=100-33*5%=66*5%`