Can someone please help me please?

How do you use the elimination method for this question? explain, because i really want to understand!

Δabc is dilated by a scale factor of 3 with the origin as the center of dilation to form δa′b′c′. the slope of is -1.2. the length of is p units, the length of is q units, and the length of is r units. the slope of is . the length of is units.

Me complete this proof! prove that a quadrilateral is a square. me with the steps for this proof.