Answer
$n\approx 4\ candy\ bars$
Work Step by Step
From tables 4-1 and 4-2
The energy requirement for a 68kg woman to ride a bycicle is $639\ Cal/h$, and the energy content of a 20g candy bar is $105\ Cal$.
For a 30g candy bar: $105\times \frac{30}{20}=157.5\ Cal$, and for 1h of cycling: $639\ Cal$
Hence:
$n=\frac{639}{157.5}=4.05\ candy\ bars$
$n\approx 4\ candy\ bars$
