A client e$-$mails you asking for advice.

She is selling T$-$shirts online featuring pictures of local murals. She charges $$15\mathrm{.}00$ per Tshirt, but she is not sure if that is the best strategy. Her sales are ok$,$ but not as high as she needs. She's already tried increasing her social media advertising to drive up sales. She's also been able to decrease her costs to about $$8\mathrm{.}00$ per shirt and doesn't think she can decrease her costs any lower.

She needs to increase her revenue and asks you what price you think she should charge.

What price do you advise her to charge per T$-$shirt?