Question 718492
The percentage representation needs to be a ratio of pure material to amount of resulting mixture.  You should use a denominator, and it must be the quantity of the mixture.

{{{(0.25x+0.35y)/60=0.32}}}

from which you can get steps:
{{{0.25x+0.35y=60*0.32}}}
{{{25x+35y=60*32}}}, then divide by 5 both sides
{{{5x+7y=12*32}}}
and you can do what you find you need.