Asap quick question : i just need to know, when you work out the length of the missing side do you put cm for the units or

Ineed with number 17 i don’t get it at alll

Afurniture manufacturer produces chairs and sofas. each chair requires 10 yards of fabric, and each sofa requires 20 yards of fabric. the manufacturer has 300 yards of fabric available. to fulfill orders, the number of sofas must be at least twice the number of chairs. let x be the number of chairs and y the number of sofas. which inequalities are described in the problem? check all of the boxes that apply

At a sale this week, a desk is being sold for $213. this is a 29% discount from the original price. what is the original price?