#1 combine like terms (algebratiles) 3y2+3y2 #2 -3x2-3x2 #3 x2-3x2

Not sure if I'm reading this correctly your post

#1 combine like terms

3y^2+3y^2 = 6y^2

#2

-3x^2-3x^2=-6y^2

#3

X^2-3x^2=-2x^2

δabc ≅ δdcb by sas because

db ≅ ac . . given (side)

bc ≅ bc . . reflexive property (side)

∠dbc ≅ ∠ acb . . alternate interior angles where transversal bc crosses parallel lines bd and ac (included angle)