An object moves from position x = -1.88 m to x = -4.27 m. what was its displacement? (unit = m)

Could someone . i have tried to solve myself but my calculation is off

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?

Which accounts for an increase in the temperature of a gas that is kept a constant volume