The sandwich shop has a total of 70 stores, this is the 100% of their stores.
90% of the stores are in California
The rest of the stores, 10%, are in Nevada.
To calculate how many stores correspond to the 90% you can use cross multiplication
100%_____70 shops
90%______x shops
[tex]\begin{gathered} \frac{70}{100}=\frac{x}{90} \\ x=(\frac{70}{100})90 \\ x=63 \end{gathered}[/tex]So the 90% of 70 is 63, this means that there are 63 stores in California.
Now subtract the number of stores in California from the total number of stores
[tex]70-63=7[/tex]And we get that there are 7 stores in Nevada
