# Prove this diophantine equation $2^a-3^b=5~，a,b\in N^{+}$ has no postive integers solution

show that the diophantine equation $$2^a-3^b=5~~~~,a>5,b>3，a,b\in N^{+}$$ has no postive integers solution

maybe is old problem,But I try somedays,can't solve it by now