Answer:
The output growth rate is 3%.
Step-by-step explanation:
Use the growth accounting equation as follow 
ΔA% = ΔY% - αΔK% - βΔL% 
Where
∆A = change in productivity = 2%
∆K = growth in capital = 
∆L = growth in labor = 
α = elasticity of capital = 0.2
β = elasticity of labor = 0.8 
∆Y = change in output = ?
Placing values in the formula
2% = ΔY% - ( 0.2 x 1% ) – ( 0.8 x 1% ) 
 2% = ΔY% - 1%
 ΔY% = 2% + 1%
ΔY% = 3% 
Hence, the output growth rate is 3%.