Answer:
 Area of each of the remaining 20 panels =  5 m²
Explanation:
 Total area of panels = 349 m²
Ā Total number of panels = 80
 Total area of 30 panels with 4 m² area = 30 x 4 = 120 m²
 Total area of 30 panels with 4.3 m² area = 30 x 4.3 = 129 m²
Ā Remaining number of panels = 20
 Remaining area = 349 - ( 120 + 129 ) = 100 m²
Area of each 20 panels = 100/20 = 5 m²
Area of each of the remaining 20 panels =  5 m²