In[1]:= f[x] = \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(0\), \(x\)]\(0.0588*
t^\((3.1)\)*Exp[\(\[Minus]0.8\)\ t] \[DifferentialD]t\)\)
Out[1]= 1.00005 - 0.146794 Gamma[4.1, 0.8 x]
In[2]:= g[x] = \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(0\), \(x\)]\(0.05181*
t^\((3.45)\)*Exp[\(\[Minus]0.87866\)\ t] \[DifferentialD]t\)\)
Out[2]= 1.00007 - 0.0921321 Gamma[4.45, 0.87866 x]
In[3]:= FindRoot[f[x] == g[x], {x, 3}]
Out[3]= {x -> 4.18645}
