In mid-May, the depth of a river in Moreland is measured. By mid-June, the river is 10 feet deeper than mid-May. By mid-July, the river is three times deeper than mid-June. If the river is 45 feet deep in mid-July, how many feet deep was the river in mid-May?
In mid-June, the river is 45/3=
<gadget id="calculator">45/3</gadget>
<output>15</output>
15 feet deep.
In mid-May, the river was 15-10=
<gadget id="calculator">15-10</gadget>
<output>5</output>
5 feet deep.

<result>5</result>