Average temperature of the whole week = 19.5° The sum of minimum temperature of 7 days = 20° + 18.6° + 17° + 21.4° + 19° + 19.8° = 115.8° Minimum temperature on Sunday = x Total temperature on the whole week = 19.5 × 7 = 136.5° Temperature on Sunday = Total temperature - Temperature of 7 days x=136°−115.8°=20.7°