If a% is the first discount and b% is the second discount on the marked price of an article, then an equivalent single discount percentage is given by:
1
\(\rm a + b-\frac{a+b}{100}\)
2
\(\rm a + b-\frac{a-b}{100}\)
3
\(\rm a + b+\frac{ab}{100}\)
4
\(\rm a + b-\frac{ab}{100}\)