Leo had some toys at first. After losing 12, he has 24 left. To find how many he had at first, add the missing toys back.<br><br>
&bull; Toys left in box = 24<br>
&bull; Toys missing = 12<br>
&bull; Toys at first = 24 + 12 = 36<br><br>
Leo had 36 toys at first.<br>
Check: 36 &minus; 12 = 24 &#10003;