Un kangourou fait des sauts de 18/5 m. Son petit saute le tiers de cette longueur. Les deux partent du point 0.

The parent kangaroo's jump length is given as $L_P = \frac{18}{5}$ m.

The baby kangaroo jumps one-third of the parent's length:

Simplify the fraction by dividing the numerator and denominator by their greatest common divisor, which is 3:

Both kangaroos start at point 0. After one jump:

• Parent kangaroo's position: $P = \frac{18}{5}$
• Baby kangaroo's position: $B = \frac{6}{5}$

The number line provided shows divisions between 0 and 1, indicating that each segment represents $\frac{1}{5}$. We need to extend this number line to place the calculated positions.

• For the baby kangaroo's position $B = \frac{6}{5}$: This can be written as a mixed number: $1 \frac{1}{5}$. On a number line divided into fifths, this position is at the first mark after the integer 1.
• For the parent kangaroo's position $P = \frac{18}{5}$: This can be written as a mixed number: $3 \frac{3}{5}$. On a number line divided into fifths, this position is at the third mark after the integer 3.

To represent this on a number line:
Draw a number line extending beyond 3. Mark integers 0, 1, 2, 3, 4.
Divide each unit segment into 5 equal parts.

• Mark the baby kangaroo's position at $\frac{6}{5}$ (which is the first mark after 1).
• Mark the parent kangaroo's position at $\frac{18}{5}$ (which is the third mark after 3).

The positions to be marked are:

• Baby kangaroo: $\boxed{\frac{6}{5}}$
• Parent kangaroo: $\boxed{\frac{18}{5}}$