A store pays $46 for a portable GPSnavigation system. The markup is 105%. Find the selling price.

the markup is the amount added to the price, to make up for other costs, like storage, store expenses and personnel and such.

so, if we take 46 to be the 100%, and then we slap on top of that 105% more, so the selling price is then 100% + 105% = 205%.

if 46 is 100%, what is the 205%?

[tex]\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 46&100\\ x&205 \end{array}\implies \cfrac{46}{x}=\cfrac{100}{205}\implies \cfrac{46\cdot 205}{100}=x[/tex]