Answer:
     [tex]\large\boxed{2hours}[/tex]
Explanation:
You will need to use the conversion between food calories, calories and joules.
    [tex]1\text { nutritional calorie }= 1,000cal\\ \\ 1cal=4.184joule[/tex]
From a nutritional table (from the internet) you can obtain the amount of nutritional calories for each type macronutrient: carbohydrates, protein, and fat.
Macronutrient    food calories
Carbohydrate     4 cal/g
Protein           4 cal/g
Fat              9 cal/g
To convert food calories to regular calories, mutiply by the conversion factor:
        [tex]1=1,000cal/\text{nutritional calorie}[/tex]
Macronutrient     calories
Carbohydrate     4,000 cal/g
Protein           4,000 cal/g
Fat              9,000 cal/g
To convert regular calories to joules, multiply by the conversion factor:
        [tex]1=4.184 joule/1cal[/tex]
Macronutrient     energy in joules
Carbohydrate     16,736 joule/g
Protein           16,736 joule/g
Fat              37,656 joule/g
Now you can multiply the grams of each macronutrient in one potato by its energy content:
Macronutrient     energy/gram   ×  grams  =  total energy
Carbohydrate     16,736 joule/g  ×  37 g    =  619,232 joules
Protein           16,736 joule/g  ×  4.3 g   =  71,968.8 joules
Fat              37,656 joule/g  ×  4 g     = 150,624 joules
Total = 619,232 joules + 71,968.8 joules + 150,624 joules = 841,820.8 joules.
Since they are two potatoes, multiply by 2: × 841,820.8 joules = 1,683,641.6 joules.
Divide by 1,000 to convert to kilojoules = 1,683.64 kilojoules
Divide the total energy from the two potatoes by the energy that an average person expend per hour of walking (845 kilojoules of energy per hour):
    [tex]1,683.64kilojoules/845kilojouesl/hour=1.99hours\approx 2hours[/tex]
