Question 864484
32		said they drove alone.
27		rode in a carpool.
28		rode public transportation.
6		used both carpools and public transportation.
7		used both a carpool and sometimes their own cars.
8		used public transportation as well as their own cars.
4		used all three methods.
Venn Diagram with known info
{{{drawing(400,400,-4,4,-5,4,
rectangle(-4,-3.5,4,4),
circle(0,-.5,2),
locate(-2,2,a),
locate(-3.5,-2,none)
locate(-1,-3,Public-28),
locate(-.3,-1,c),
locate(1.1,.4,6),
circle(sqrt(2),sqrt(2),2),
locate(-4,4,Drivealone-32),
circle(-sqrt(2),sqrt(2),2),
locate(2,4,Carpool-27),
locate(-1.3,.5,8),
locate(0,2.5,7),
locate(2,2,b),
locate(-.2,1.1,4) )}}}
alone

7 carpools and alone
8 public transportation and alone
4 all three ways
total 32-19=13 =a only alone

carpool
7 carpools and alone
4 all three ways
6 carpool and bus

27-17=10 =b only carpool
public transportation
8 public transportation and alone
4 all three ways
6 carpool and public transportation
28-18=10 =c only public transportation

Shared 8+4+6+7=25
13+10+10=33
25+33=58
100-58=42 =none 
Venn Diagram with calculated info
{{{drawing(400,400,-4,4,-5,4,
rectangle(-4,-3.5,4,4),
circle(0,-.5,2),
locate(-2,2,13),
locate(-3.5,-2,42)
locate(-1,-3,Public-28),
locate(-.3,-1,10),
locate(1.1,.4,6),
circle(sqrt(2),sqrt(2),2),
locate(-4,4,Drivealone-32),
circle(-sqrt(2),sqrt(2),2),
locate(2,4,Carpool-27),
locate(-1.3,.5,8),
locate(0,2.5,7),
locate(2,2,10),
locate(-.2,1.1,4) )}}}
none of above might be walking, bike, skateboard, roller skates, or motorbike