Chris needs to make a 500 l of a 35% acidic solution. he has only two of the acidic solutions available, a 25% solution and a 50% solution. how many litres of each acidic solution should he mix? create a system to solve?

Yes, very fun, not

ok
one way is table or

solutions amount x and y
x+y=500
x=25%
y=50%
0.25x+0.5y=0.35(500)

we have
x+y=500
0.25x+0.5y=0.35(500)
0.25x+0.5y=175
solve

multiply second equation by 100
25x+50y=17500
divide everybody by 25
x+2y=700

now we have
x+y=500
x+2y=700

multiply first equation by -1 and add to second equaiton

-x-y=-500
x+2y=700 +
0x+1y=200

y=200
sub
x+y=500
x+200=500
x=300

300L of the 25% and 200L of the 50%