A radiator contains 10 quarts of fluid, 30% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 60% antifreeze?

v30% mixture + v100% mixture = v60% mixture

0.3(10-x) + x = 0.6(10)
3 - 0.3x + x = 6
0.7x = 6 - 3
0.7x = 3
x = 3/0.7
x = 4.286 quarts