Doreen is 3/4 mile from the Library.
Sheila is 1/3 as far as Doreen.
well, what's 1/3 of 3/4? well, is simply their product, so (1/3) * (3/4) = 1/4.
meaning Sheila is 1/4 mile as far as Doreen.
well, Doreen is 3/4 of a mile away, so Sheila is then 3/4 + 1/4 = 1 whole mile away from the Library.
is Sheila farther than Doreen from the Library?
of course, 1 mile > 3/4 mile.
does Sheila live 1/4 of a mile from the Library?
well, you already know how far Sheila is, check above.
is Sheila twice as farther than Doreen?
Doreen is 3/4 mile away, Sheila is 1 mile away, 1 mile is not twice as much of 3/4.