First we calculate the return on equity(ROE) based on the Du-pont equation
ROE = Net profit margin * Total asset turnover * equity multiplier
Total asset turnover = 1/capital intensity =1/1.08
Equity multiplier = 1+ debt to equity = 1+ 0.54 = 1.54
net profit margin = 6.2% = 0.062
ROE = 0.062*1/1.08*1.54 = 0.0884 = 8.84%
Sustainable growth rate = ROE*(1- dividend payout)
Sustainable growth rate = 0.0884*(1-0.4)
Sustainable growth rate= 0.053 = 5.3%
Sustainable growth rate = 5.30%