Respuesta :

$ 40 ..... 100 %
$ 28 ..... x %

[tex]x = \frac{28 \cdot 100}{40} = 70[/tex]

The % of change is 70 %.

This is equivalent with:
- the final price ($ 28) is 70 % from the initial price ($ 40)
- the initial price ($ 40) was reduced with 30% giving the new price as:
[tex]40 - 40 \cdot \frac{30}{100} = 28[/tex]
$28/$40•x/100
100 times $28 is 2800 so then 2800 divided by $40 which would be 70 so the percentage would be 70