What is the solution to this system of linear equations y-x=4 and y+2x=1

In the field of thermodynamics, rankine is the unit used to measure temperature. one can convert temperature from celsius into rankine using the formula c= r/1.8 - 273, what is the temperature in celcius corresponding to r degrees rankine.

Me with geometry ! in this figure, bc is a perpendicular bisects of kj. dm is the angle bisects of bdj. what is the measure of bdm? •60° •90° •30° •45°

Which of the following is not a subset of {1,2,3}?