Tolong pakai cara yaa;)

Banyak bahan bakar awal = 100%
hari pertama = 100% - 65%
                     = 35%

hari kedua = 35% - 1/5
                  = 0,35 - 0,2
                  = 0,15
                  = 15/100
                  = 15 %  [A]

20%+65%= 85%
100%-85%= 15%
A. 15%