Ireally need someone to explain to me how to solve these types of equations. my teacher has been out a lot and i've been completely lost!

In pqr the obtuse angle is 105 and the shorter sides measure 4 and 7 units rounded to the nearest tenth what is the area of triangle pqr

What is the value of the digit 1 in the number 13?

What will the graph look like for a system of equations that has no solution? a. the lines will be perpendicular. b. the lines will cross at one point. c. both equations will form the same line. d. the lines will be parallel.