Question

By increasing the speed of her car  by 5 km/h, Alice was able to drive 12 km in 0.2 hours.  What was her original speed?

Answer 1

$v=\frac{s}{t}\\\\v-speed\\s-distance\\t-time\\\\s=12km;\ t=0.2h\\\\v=\frac{12}{0.2}\ km/h=\frac{120}{2}\ km/h=60\ km/h\\\\60\ km/h-5\ km/h=55\ km/h\\\\Answer:Her\ original\ speed\ was\ 55\ km/h.$

Answer 2

Alice's driving speed  =  distance driven / time taken
               =  12 km / 0.2 hours  =  60 km per hour  = 60 kmph

She increased the speed by 5 kmph and then it became 60 kmph

So her speed earlier was less by 5 kmph
               = 60 kmph - 5 kmph  = 55 kmph