Im stuck on the last part of the question and I really need some guidance! I've completed a and b$,$ now I have the last part left. It asks me to calculate the average actual warranty cost per unit for the $3-$year period, but the I don't know how to calculate it$.$

Here's some background info: On Jan $1,2022,$ Carla Vista Company began a warranty program to simulate slaes will be returned for repair at an esitmated cost of $$36$ per unit. Sales and warranty figures for the $3$ years ended December $31$ are as follows $($shown in the table in the picture$).$

This is part a of the question that I've answered:

Calculate the warranty expense for each year and warranty liability at the end of each year. $(2$nd table$)$

Now the question asked me for the average actual warranty cost per unit for the $3$ year period, but I am unsure how to calculate this. Please help!