The speed of sound in air, symbol v, is approximately constant at 340 metres per second. (You do not need to memorise this value.) As temperature increases, the speed increases slightly.
Speed, frequency and wavelength are related by the formula v = f × λ. Other forms of this relationship are f = v/λ and λ = v/f. Because the speed is approximately constant, it follows that frequency and wavelength are inversely proportional: doubling the frequency halves the wavelength, etc.