So the car is moving at 651 revolutions per minute, with wheels of a radius of 18inches
so, one revolution, is just one go-around a circle, and thus 2π, 651 revolutions is just 2π * 651, or 1302π, the wheels are moving at that "angular velocity"
now, what's the linear velocity, namely, the arc covered per minute
well
![\bf v=rw\qquad \begin{cases} v=\textit{linear velocity}\\ r=radius\\ w=\textit{angular velocity}\\ ----------\\ r=18in\\ w=1302\frac{\pi }{min} \end{cases}\implies v=18in\cdot \cfrac{1302\pi }{min} \\\\\\ v=\cfrac{23436\pi\ in}{min}](https://tex.z-dn.net/?f=%5Cbf%20v%3Drw%5Cqquad%20%0A%5Cbegin%7Bcases%7D%0Av%3D%5Ctextit%7Blinear%20velocity%7D%5C%5C%0Ar%3Dradius%5C%5C%0Aw%3D%5Ctextit%7Bangular%20velocity%7D%5C%5C%0A----------%5C%5C%0Ar%3D18in%5C%5C%0Aw%3D1302%5Cfrac%7B%5Cpi%20%7D%7Bmin%7D%0A%5Cend%7Bcases%7D%5Cimplies%20v%3D18in%5Ccdot%20%5Ccfrac%7B1302%5Cpi%20%7D%7Bmin%7D%0A%5C%5C%5C%5C%5C%5C%0Av%3D%5Ccfrac%7B23436%5Cpi%5C%20in%7D%7Bmin%7D)
now, how much is that in miles/hrs? well
let's keep in mind that, there are 12inches in 1foot, and 5280ft in 1mile, whilst 60mins in 1hr
thus
![\bf \cfrac{23436\pi\ in}{min}\cdot \cfrac{ft}{12in}\cdot \cfrac{mi}{5280ft}\cdot \cfrac{60min}{hr}\implies \cfrac{23436\cdot \pi \cdot 60\ mi}{12\cdot 5280\ hr}](https://tex.z-dn.net/?f=%5Cbf%20%5Ccfrac%7B23436%5Cpi%5C%20in%7D%7Bmin%7D%5Ccdot%20%5Ccfrac%7Bft%7D%7B12in%7D%5Ccdot%20%5Ccfrac%7Bmi%7D%7B5280ft%7D%5Ccdot%20%5Ccfrac%7B60min%7D%7Bhr%7D%5Cimplies%20%5Ccfrac%7B23436%5Ccdot%20%5Cpi%20%5Ccdot%2060%5C%20mi%7D%7B12%5Ccdot%205280%5C%20hr%7D)
notice, after all the units cancellations, you're only left with mi/hrs