Final answer:
The mathematical sentence that expresses the information given is t + 6 = 84, where t represents the temperature at 11:00 am. Solving this equation gives us t = 78 degrees, which is the temperature recorded by Nina at 11:00 am.
Step-by-step explanation:
To express the information given in the question mathematically, we can set up an equation. If t is the temperature at 11:00 am that Nina checks, and knowing that an increase by 6 degrees would break the record high of 84 degrees, we write:
t + 6 = 84
This equation means that if we add 6 degrees to the temperature at 11:00 am (t), it will equal the record high temperature of 84 degrees. To solve for t, we simply subtract 6 from both sides of the equation. Therefore, the temperature at 11:00 am according to the equation would be:
t = 84 - 6
t = 78 degrees
So, Nina recorded a temperature of 78 degrees at 11:00 am.