never mind ! my bad

> d := p -> 68 - exp(0.04 p) d := p -> 68 - exp(0.04 p) > > s := p -> (20/3)* ln(135, 2 p) s := p -> (20/3)* ln(135, 2 p) > solve({d(p) = s(p)}, p) Error, (in ln) expecting 1 argument, got 2 > why do I get this error ? and how can I fix it