Question

The cost CC (in dollars) of making nn watches is represented by C=15n+85C=15n+85. How many watches are made when the cost is $385?

Answer 1

$\bf \stackrel{cost}{C}=15\stackrel{watches}{n}+85\qquad \boxed{C=385}\qquad \stackrel{cost}{385}=15n+85 \\\\\\ 380=15n\implies \cfrac{380}{15}=n\implies \cfrac{76}{3}=n\implies 25\frac{1}{3}=n$

so, 25 whole watches and hmmmm just the wristband of another maybe.