so if x people were surveyed, [tex] \frac{7}{8} [/tex] people owned a bike and [tex] \frac{1}{8} [/tex] did not.
The difference between them is 72:
[tex] \frac{7}{8} [/tex] x-\frac{1}{8} [/tex] =72
so this means that
[tex] \frac{6}{8} [/tex] x=72
let's simplify:
[tex] \frac{3}{4} [/tex] x=72
and divide by 3:
[tex] \frac{1}{4} [/tex] x=24
and mupliply by 4:
x=96
so 96 people were surveyed