The angels 60, a, and 55 are supplementary, meaning they add up to 180 degrees.
Therefore we have
[tex]60+a+55=180[/tex]
Solving for a gives us
[tex]\textcolor{#FF7968}{a=65.}[/tex]
Now, we know that the sum of angles in a triangle is 180 degrees; therefore,
[tex]a+b+90=180[/tex]
since a = 65, we have
[tex]65+b+90=180[/tex]
solving for b gives us
[tex]\textcolor{#FF7968}{b=25.}[/tex]
The angle c is opposite the angle b; therefore, it is
[tex]\textcolor{#FF7968}{c=25.}[/tex]
Angles d and 15 are complementary meaning they add up to 90; therefore, we have
[tex]15+d=90[/tex][tex]\textcolor{#FF7968}{\therefore d=75}[/tex]
