Concept:
Count only the
legs touching the ground. Riders do not contribute their legs to the ground count, while walking men and all horses do.
Step 1:Let total number of men = total number of horses = $x$.}
Half of the men are riding $\Rightarrow \frac{x}{2}$ men are on horses.
Remaining $\frac{x}{2}$ men are walking.
Step 2:Count legs on the ground.}
- Each horse has 4 legs $\Rightarrow$ total horse legs = $4x$
- Walking men = $\frac{x}{2}$, each has 2 legs $\Rightarrow$ total = $2 \times \frac{x}{2} = x$
Total legs on ground:
\[
4x + x = 5x
\]
Step 3:Form equation.}
\[
5x = 70
\Rightarrow x = 14
\]
Final Answer:
\[
{14}
\]