Question 866607
since it is right triangle

x^2+(x-51)^2=75^2 ( Pythagoras theorem)

x^2+x^2-102x +2601= 5625

2x^2-102x-3024=0

/2
x^2-51x-1512=0

x^2-72x+21x-1512=0

x(x-72)+21(x-72)=0

(x-72)(x+21)=0

x=72 OR -21

ignore negative
x= 72