Question 773436
Two equations which rely on each other.  One equation accounts for salt and the other equation accounts for mixture.
Let x = ounces of solution A
Let y = ounces of solution B


Accounting for salt:
{{{0.25x+0.50y=0.40*150}}} quantity of salt, in ounces. 
{{{0.25x+0.50y=60}}}
divide left&right by 5,
{{{0.05x+0.10y=12}}}
eliminate fractions multiply by 100,
{{{5x+10y=1200}}}


Account for mixture:
{{{x+y=150}}}  for ounces of mixture.


SOLVE THE SYSTEM:
{{{5x+10y=1200}}} and {{{x+y=150}}}