#### Answer

(a) $21^o$ F
(b) $0^o$ F

#### Work Step by Step

Use the table to find the "windchill" temperature.
(a)
$30^o$ F is in the 4th column while $10$ mph wind is in the 3rd row of the first column.
The intersection of the 3rd row and the 4th column is $21$.
Thus, the "windchill" temperature is $21^o$ F.
(b)
$15^o$ F is in the 7th column while $15$ mph wind is in the 4th row of the first column.
The intersection of the 4th row and the 7th column is $0$.
Thus, the "windchill" temperature is $0^o$ F.