Simplify these problems to me understand on how to do the problems

3/4/9/x^2
4/u/u^2/16

Asmall foreign car gete 42 miles per gallon and user 35 gallons on a trip. gasoline costs $1.05 per gallon. what was the cost of gasoline per mile driver?

Martin likes to make flower bouquets that have 3 daffodils and 4 tulips per vase. a daffodil has a mass of d grams, a tulip has a mass of t grams, and the vase has a mass of u grams. the expression 5(3d + 4t + v) describes the mass of 5 bouquets. match each amount in the situation with the expression that represents it. situation expression number of bouquets mass of one bouquet mass of the tulips in one bouquet 4t mass of the daffodils in one bouquet 3d + 4t + v

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?