Optical signal processing is considered to be a promising technique to overcome the speed limitation of electronics and accelerate next-generation high-speed optical networks. Among various optical signal processing operations, optical arithmetic functions have attracted increasing interest. Here, by exploiting the degenerate four-wave mixing progress in graphene and adopting (differential) quadrature phase-shift keying signals, we experimentally demonstrate 10 Gbaud two-input (A, B) hybrid quaternary arithmetic functions of doubling and subtraction (2A-B, 2B-A) in the optical domain. The measured optical signal-to-noise ratio penalties at a bit-error rate of 2 × 10⁻³ are about 7.4 dB for 2A-B and 7 dB for 2B-A.