Original cost: 45$; markup%: 20% ( the first one) do fast my test is coming any

Two blends of tea are mixed to make a blend that will be sold at the fair. black tea sells for $2.20 per pound and orange pekoe tea sells for $3.00 per pound. how much of each should be used to obtain a 4lb blend selling for $2.50 per pound?

You are at a restaurant and owe $38 for your meal. you want to leave a 20% tip. how much will your tip be?

How many different three-digit numbers can be formed using the digits 1 comma 2 comma 9 comma 6 comma 4 comma 3 comma and 8 without repetition? for example, 664 is not allowed.