Question 719977
Let {{{ p }}} = the original price
With discount:
price = {{{ p - .3p }}}
{{{ p - .3p = .7p }}}
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Let {{{ x }}} = the fraction that the discounted price must be 
increased by to equal the original price
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{{{ .7p + x*( .7p ) = p }}}
Divide both sides by {{{ p }}}
{{{ .7 + .7x= 1 }}}
{{{ .7x = .3 }}}
{{{ x = 3/7 }}}
{{{ x =  .4286 }}}
The discounted price is increased by .4286
or 42.86% to equal the original price
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check Suppose the original price was $70
{{{ 70 - .3*70 = 70 - 21 }}}
{{{ 70 - 21 = 49 }}}
and
{{{ 49 + .4286*49 = 49 + 21.0014 }}}
{{{ 49 + 21.0014 = 70.0014 }}}
close enough