Thread: Help with this Word Problem

During cold weather, a car with a 20 Liter radiator containing 10% antifreeze must increase the solution to 25% antifreeze. How many liter of 10% antifreeze must be drained and replaced with 100% antifreeze?

Let x L be removed so remaining is (20 – x)
and Let x L of 100% antifreez be relpaced.
(20 – x) × 10/100 + × x 100/100 = 20 × 25/100
2 – 0.1x + ×= 5
0.9x = 3
x = 3 1/3 L be replaced.
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