Question 681415
Two Ways To Solve 
First Way: Unit Conversion
{{{(90miles/hour)*(1hour/60minutes)=(1.5mi/min)}}}
Then times 20 minutes by new units
{{{20min*(1.5mi/min)=30 miles}}}
Second Way:
Notice that 20 minutes is {{{1/3}}} of a hour. So in {{{1/3}}} the time you go {{{1/3}}} the distance which is {{{90*(1/3)=30 miles}}}