A $10.00 3-leg multi at 6.98 returns $69.83 if every leg wins. The prices give that about a 14.3% chance.
Combined odds
6.98
3 legs
Total return
$69.83
stake included
Profit
$59.83
Margin built in
~14%
at 5% a leg

Calculator by HaterPicks · information, not advice · 18+