How was distrubutive property used to create an expression that is equivalent to 3f +2f

What is the approximate total length of iron edging needed to create the square frame and the two diagonals?

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much

Find the volume of the solid obtained by rotating the region enclosed by the curves y=1x and y=7^-x about the x-axis. (use symbolic notation and fractions where needed.) volume =