Sorry, I have done this the wrong way around. Sorry
I'll do it again
original price = $30
new price = $31.50
Markeup = (31.50-30)/30 * 100 percent =5%
$${\frac{\left({\mathtt{31.5}}{\mathtt{\,-\,}}{\mathtt{30}}\right)}{{\mathtt{30}}}}{\mathtt{\,\times\,}}{\mathtt{100}} = {\mathtt{5}}$$
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