Question 159745
The first piece is {{{x}}} inches long.  The second piece is 3 inches longer than that, or {{{x+3}}}.  The third piece is 4 inches longer than the second, so {{{x+3+4=x+7}}}.  The length of the three pieces together is {{{x+(x+3)+(x+7)=64}}}.


Combine terms and solve:  {{{3x+10=64}}}


I'll leave it to you to finish.