How to break a noun phrase into two constituent parts​

Which of the following is a complex sentence? a. after henry submitted his essay, he realized that he hadn't proofread the last page. b. identity theft is a growing problem, especially among seniors. c. we didn't have enough potatoes for dinner, so we served rice instead. d. jim tried to watch a video on a device connected to a crowded wireless network; as a result, the video stuttered and froze.

If one writes logically, he will prove his point. is this sentence correct or contains an unwarranted shift in person?

Type the correct answer in the box. use numerals instead of words. if necessary, use / for the fraction bar. the length of each side of a square increases by 2.5 inches to form a new square with a perimeter of 70 inches. the length of each side of the original square was inches.