$1.$A store sells a breadmaker for a regular price of $$90,$ which produced a $25\%$ gross profit on cost$.$ During a sale, the price was reduced so that the sale price produced a $10\%$ gross profit on sales. What was the cost?

$2.$ A store sells a breadmaker for a regular price of $$90,$ which produced a $25\%$ gross profit on cost$.$ During a sale, the price was reduced so that the sale price produced a $10\%$ gross profit on sales. What was the sale price?

$3.$ Julio's Interiors marks its furniture to obtain a markup of $33\mathrm{.}33\%$ of the selling price. During a sale, a sofa that cost $$424$ received a $20\%$ reduction off its regular price. What was the regular marked price of the sofa? Round your answer to $2$ decimal places.

$4.$Julio's Interiors marks its furniture to obtain a markup of $33\mathrm{.}33\%$ of the selling price. During a sale, a sofa that cost $$424$ received a $20\%$ reduction off its regular price. What was the sale price? Round your answer to $2$ decimal places.

$5.$ At an after$-$holiday sale, a store marked a crystal clock down $15\%,$ making the sale price $$51.$ At this sale price, the store made a $20\%$ gross profit on sales. Find the cost.

$6.$ At an after$-$holiday sale, a store marked a crystal clock down $15\%,$ making the sale price $$51.$ At this sale price, the store made a $20\%$ gross profit on sales. Find the percent markup on the regular selling price.

$7.$ A store paid $$40$ each for fifty $35$mm cameras. It sold $40$ cameras for $$55$ each. The price for the last $10$ cameras was $$35$ each. The regular markup for overhead was $20\%$ on cost$.$ How much a net profit $($or an operating loss$)$ made on the $50$ cameras?