Please someone answer this question

Dear Student,
A car travelled a distance of x = 70 km in $t = 86 min = \frac{86}{60}h$
Slope of the distance time graph, $\frac{dx}{dt}=speed of the car = \frac{70 km}{86/60 h}= \frac{70\times 60}{86}=48.84 km/h$
Regards