Answer: x=12
Step-by-step explanation:
we know that sum of a triangle is 180 degrees
one angle is 90 degree
the sum will be 90+(2x+1)+(5x+5)=180
substract 90 from both sides
2x+1+5x+5=180-90
7x+6=90
7x=90-6
divide by 7
x=12
