Plug y= x+5 in 3x+y= 25, we have:
3x+ (x+5)= 25
⇒ (3x+x)+ 5= 25 (combine like terms)
⇒ 4x= 25-5
⇒ 4x= 20
⇒ x= 20/4
⇒x= 5
y= 5+5= 10
Final answer: x=5, y=10~
M=-3/11 by the Slope Formula.
Choice A is correct
BC=DC
the two triangles share one angel C
the two triangles each have a right angle
so they are congruent according to Angle-Side_Side Theorem
You use the lower case letter s for the sample standard deviation
You use the greek letter sigma (written as

) for the population standard deviation
I know number 15 is right