Do all functions have a dependent variable

Under normal conditions, 1.5 feet of snow will melt into 2 inches of water. during a winter season high in the mountains, 301 feet of snow fell. how many inches of water will there be when the snow melts?

Solve the given system of equations. 2y= -x+9 , 3x-6= -15

Write an algebraic expression to match each statement a. four less than 8 times a number b. twice the difference of a number and six c. nine from a number squared