At the store, Sam bought 4 hats for $65. What is the cost of 1 hat?

Ithink i know it but i want to be sure so can you me out ?

How many liters of peroxide should be added to 12 liters of an 8% peroxide solution so that the resulting solution contains 16% peroxide?   original added new amount of peroxide 0.96 liters x 0.96 + x amount of solution 12 liters x 12 + x 0.18 liter 1.14 liters 1.92 liters 2.10 liters

Agrasshopper weighs 0.89 grams. express the grasshopper’s weight in scientific notation.