Successive discounts of p% and q% on the catalogue price of an article la equivalent to a single discount of :
1). $\left(x-y-\frac{xy}{100}\right)$%
2). $\left(p-q-\frac{pq}{100}\right)$%
3). $\left(p+q-\frac{pq}{100}\right)$%
4). $\left(p+q+\frac{pq}{100}\right)$%