Look Ahead To find the new temperature, you found the sum of a positive anda negative integer. You can use a number line to help you think about addinga. During the day, the temperature at another weather station is 4°C. Overnight,it changes by-9°C Enrico models the situation on the number line below.Hasina says she can model it with one arrow. How can she model the situationLook Back whalHow do you know?positive and negative numbers.with just one arrow?434520 1-3 -2 -1