Anyone know a easy way to do this word problem

A farmer has a 3% solution and an 8% solution of pesticide. How much of each must he mix to get 2000 L of 4% solution for his sprayer?

Let x be the volume of 3% solution and y be the volume of 8% solution.
1) x + y = 2000 or x = 2000 - y
2) 0.03x + 0.08y = 0.04(2000)
substitute eq(1) into eq(2):
0.03(2000 - y) + 0.08y = 80
60 - 0.03y + 0.08y = 80
0.05y = 20
y = 20/0.05 = 400L
using eq(1):
x = 2000 - 400 = 1600L
check using eq(2):
0.03(1600) + 0.08(400) = 80
48 + 32 = 80
80 = 80
Mix 1600L or 3% with 400L of 8%.

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