Answer
2.62 MeV
Work Step by Step
By conservation of mass-energy, the photon energy equals the mass energy of the products plus the kinetic energy of the products. The positron and electron have equal mass.
$$E_{photon}=KE_{products}+m_{e}c^2+m_{pos}c^2$$
$$ KE_{products}=E_{photon}-2\times m_{e}c^2$$
$$ KE_{products}=3.64MeV-2(0.511MeV)=2.62 MeV$$