if we want to calculate the full prize we need to calculate how much the tax was:
420* 17[tex] \frac{1}{2} [/tex]%=420*[tex] \frac{175}{1000} [/tex]=420*[tex] \frac{7}{40} [/tex]=21*[tex] \frac{7}{2} [/tex]=73.5
so this is how much the tax was.
and the full prize is the cost of the ring and the tax: 420+73.5=493.5
so that's how much the buyer will pay
