3/4 of 7 pints were used. of, in this case, means to multiply. 3/4 x 7= 21/4= 5 and 1/4 pints. Now we subtract 5 and 1/4 (because this is how much was used) from 7. 7- 5 and 1/2 = 1 and 1/2
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So if 360 is increased by 25%, you would end up with 450 (360 x 1.25), than if the result, 450 is decreased by 50% ( 450 x .50 = 225) (450 - 225 = 225) you would end up with 225.