Maria is climbing a mountain. Maria's elevation, E (t), in feet after t minutes is given by E (t) = 1200 + 40t.

Interpret the meaning of E (15) = 1800 in the context of the problem.

E (t) is the elevation Maria is at at t minutes.

The expression to calculate the elevation is 1200 + 40t.

E (t) = 1200 + 40t

E (15) means the elevation Maria is at at time 15 minutes.

E (15) = 1200 + 40 (15)

E (15) = 1200 + 600

E (15) = 1800

E (15) = 1800 means that Maria is at an elevation of 1800 ft after 15 minutes.