During the summer months the water level in Marta's pool decreases by about 1/2 inch each day due to evaporation. Which equation shows the total change, in inches, to the water level in her pool after 30 summer days?

Change = - (1/2) * 30 = - 15 inches

Step-by-step explanation:

If the water level decreases by 1/2 inch each day, the change in the water level in one day is - 1/2 inch.

So, after t days, the total change in the water level can be calculated as:

Total change = - (1/2) * t inches

So, after 30 summer days, the total change is:

Change = - (1/2) * 30 = - 15 inches

So the water level of the pool after 30 summer days has decreased by 15 inches.