Storm Center 7 was tracking a cold front approaching Cedarburg. Before it rolled in, the temperature

Storm Center 7 was tracking a cold front approaching Cedarburg. Before it rolled in, the temperature was – 7°F. Then, the temperature decreased by 9°F. What was the temperature after the cold front rolled in?

Using signed integers, we start with 7 below or -7
-7

The temperature decreased by 9 which means we subtract:
-7 - 9 or -7 + (-9)
-16°F or 16 below 0