1. Conversion factor (k)=desired yield ÷ original yield
4 servings (k₄)

80 servings (k₈₀)

2. Once you have the convertion factors you have to multiply each ingredient by the corresponding k to get the correct amounts for the desired servings.
I'll start with all ingredients for 4 servings:
k₄=1/2
Flour
1 1/2 cups= 3/2 cups

For 4 servings you need 3/4 cups of flour
Baking powder
1 tbs * k₄=1 * 1/2= 1/2 tbs
For 4 servings you need 1/2 tbs baking powder
Salt
1/4tsp*k₄=1/4*1/2=1/8 tsp salt
Cinnamon
1/2 tsp * k₄= 1/2*1/2= 1/4 tsp cinnamon
Nutmeg
1/8 tst * k₄= 1/8*1/2= 1/16 tsp nutmeg
Egg
1 egg * k₄= 1 * 1/2= 1/2 Egg
Sugar
1/2cup *k₄= 1/2*1/2= 1/4 cup sugar
Buttermilk
1/2cup * k₄= 1/2*1/2= 1/4cup buttermilk
Vegetable Oil
1/4cup * k₄= 1/4*1/2= 1/8 cup vegetable oil
Vanilla
1/2tsp * k₄= 1/2*1/2= 1/4 tsp vanilla
Chocolate chips
3/4 cup * k₄= 3/4*1/2= 3/8 cup chocolate chips