Question 149891
y=liters 2%
x=liters 10%
coefficient=percent


2y+10x=4(30)
2y+10x=120


y+x=30



So you have two equations:
2y+10x=120
y+x=30


Solve for y in the second equation
y=30-x


Plug that into the first equation
2(30-x)+10x=120


Distribute
60-2x+10x=120


Combine like terms
60+8x=120


Subtract 60 from both sides
8x=60


Divide by 8
x=60/8 or 15/2


y=30-x
y=30-15/2
y=60/2-15/2
y=45/2


liters 2%=22.5
liters 10%=7.5