What is the lcd for fractions

5/7 and 1/21. ?

How far could you drive on 50 gallons of gas

Find the volume of the solid whose base is the region bounded by f(x), g(x) and the x-axis on the interval [0, 1], and whose cross-sections perpendicular to the y-axis are squares. your work must show the integral, but you may use your calculator to evaluate it. give 3 decimal places for your answe

Micheal is 4 times as old as brandon and is also 27 years older than brandon. how old is micheal