Question 181259
{{{N[1]*s[1]=N[2]*s[2]=N[3]*s[3]}}}
{{{48*5=20*s[2]=16*s[3]}}}
{{{s[2]=12}}}
{{{s[3]=15}}}
Yes, you found the speed of all of the gears. 
What is the speed of the smallest gear? That's the original question.