a^2+b^2=c^2 where c=25 m. and a=2b-10 m. substitute (2b-10)^2+b^2=25^2 4b^2-40b+100+b^2=625 5b^2-40b+100=625 divide both sides by 5 b^2-8b+20=125 subtract 20 from both sides b^2-8b=105 complete the square take half of 8 and square it=16 i hope this helps =3