Answer:
1. 142.1 GPa
2. 98.52%
Explanation:
1. The modulus of elasticity of carbon-epoxy composite is calculated using the following formula:
Ec = VmEm + VfEf
where Vm: volume of Epoxy
      Em: modulus of the elasticity of the epoxy
      Vf: volume of carbon fiber
       Ef: modulus of the elasticity of the carbon fiber
Given that :
     Vm = 0.6
      Em = 3.5 GPa
      Vf = 0.4
       Ef: 350 Gpa
Therefore Ec = (0.6 × 3.5 GPa + (0.4 × 350 GPa)
Ec = 142.1 GPa
The modulus of elasticity of carbon-epoxy composite is 142.1 GPa
2. Percentage of load carried by the carbon fibers is given by the following equation: Ff/Fc = (Ef/Ec)×Vf
where Ff is the force carried by carbon fibers, Fc is the force applied to the composite, Ec is the modulus of elasticity of the composite,  Ef is the  modulus of the elasticity of the carbon fiber and Vf  the volume of carbon fiber.
Given that:
    EF = 350 Gpa
    Ec = 142.1 GPa
     Vf = 0.4
Substituting the above values into the equation:
Ff/Fc = (350 GPa/142.1 GPa)×0.4 = 0.9852 = 98.52%
The percentage of load carried by the carbon fibers is there 98.52%
