Answer:
option: A($70)
Step-by-step explanation:
We are given Selling Price(S.P.) of the goods=$21
Let the cost price(C.P.) of the goods be denoted by 'x'.
Also we are given that the loss percentage is equal to the C.P.
i.e.
[tex]loss\%=\dfrac{CP-SP}{CP} \times 100[/tex]
[tex]CP=\dfrac{CP-21}{CP}\times 100[/tex]
[tex]x=\dfrac{x-21}{x}\times 100[/tex]
[tex]x^{2}=100x-2100\\ \\x^{2}-100x+2100=0\\\\x^{2}-70x-30x+2100=0\\ \\x(x-70)-30(x-70)=0\\\\(x-70)(x-30)=0[/tex]
This means that x=70 or x=30
Hence from the options given we could say that the cost price of goods is $70.
Hence option A is correct.
