Final answer:
The percent change in the area of the final photo is 17%.
Step-by-step explanation:
To find the percent change in area, we need to calculate the change in area and divide it by the original area.
Let's say the original length of the cover photo is 'L' units and the original width is 'W' units. The original area is then given by 'A = L * W'.
The photographer increased the length by 30%, which means the new length is '1.3L'. The width was decreased by 10%, which means the new width is '0.9W'.
The new area is given by 'A_new = (1.3L) * (0.9W) = 1.17LW' units.
The change in area is 'A_new - A = 1.17LW - LW = 0.17LW' units.
To find the percent change, we divide the change in area by the original area and multiply by 100:
Percent change = (0.17LW / LW) * 100 = 17%.