For Quantity A, the original price is equal to 30% less than $250, which means 70% of $250, which translates as .7x$250. The selling price was 20% below that, which means 80% of that, which translates as .8x.7x$250.

For Quantity B, 50% of the $250 translates as .5x$250.

So we have an inequality:

.8x.7x$250 vs. .5x$250

We can divide out the $250 and ignore it, leaving us with .8x.7 vs. .5. Since .8x.7 equals .56, A must be bigger.