In the rhombus, the diagonals are perpendicular.
We know, the sum of the measures of the triangle is equal 180°.
Therefore we have the equation:
[tex](2x-15)+3x+90=180[/tex]
[tex]2x-15+3x+90=180[/tex] combine like terms
[tex](2x+3x)+(-15+90)=180[/tex]
[tex]5x+75=180[/tex] subtract 75 from both sides
[tex]5x=105[/tex] divide both sides by 5
[tex]\boxed{x=21}[/tex]
Answer: x = 21°
