Answer:
x=25
Step-by-step explanation:
a triangles angles total to 180
we know we have one right angle, thats 90 degrees taken
90 degrees r now left
we combine the x'es, so now we have 3x+15
after subtracting 15 from 90, we have 75
so now our equation is 3x=75
75÷3=25
x=25
