Find angle a

this is so confusing I've asked 3 tutors and they all don't know how to do this​

Koji is installing a rectangular window in an office building. the window is 823 feet wide and 534 feet high. the formula for the area of a rectangle is a=bh. what is the area of the window? enter your answer as a mixed number in simplest form in the box. $$ ft2

The ph level of a blueberry is 3.1 what is the hydrogen-ion concentration [h+] for the blueberry

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.