How many tenths are there in 4/5?

3.4a=57.8 what is the the value of a

Asmall book publisher knows that 26 books weigh 41 lbs. how much do 40 books weigh?

Becca wants to mix fruit juice and soda to make a punch. she can buy fruit juice for $3 a gallon and soda for $4 a gallon. if she wants to make 28 gallons of punch at a cost of $3.25 a gallon, how many gallons of fruit juice and how many gallons of soda should she buy?