Edit: assuming the following (starting top left, clockwise): R4, R10, R6, R5
[area of rectangle] - [area of corner cutouts]
(20 x 30) - {[(8^2)-(pi*4^2)]/4} - [(pi*10^2)/4] - {[(12^2)-(pi*6^2)]/4} - [(pi*5^2)/4]
= 600 - (3.4) - (78.5) - (7.7) - (19.6)
= 490.8
[area of rectangle] - [area of corner cutouts]
(20 x 30) - {[(8^2)-(pi*4^2)]/4} - [(pi*10^2)/4] - {[(12^2)-(pi*6^2)]/4} - [(pi*5^2)/4]
= 600 - (3.4) - (78.5) - (7.7) - (19.6)
= 490.8
[area of rectangle] - [area of corner cutouts]
(20 x 30) - {[(8^2)-(pi*4^2)]/4} - [(pi*10^2)/4] - {[(12^2)-(pi*6^2)]/4} - [(pi*5^2)/4]
[area of rectangle] - [area of corner cutouts]
(20 x 30) - {[(8^2)-(pi*4^2)]/4} - [(pi*10^2)/4] - {[(12^2)-(pi*4^2)]/4} - [(pi*5^2)/4]
[area of rectangle] - [area of corner cutouts]
(20 x 30) - {[(4^2)-(pi*4^2)]/4} - [(pi*10^2)/4] - {[(6^2)-(pi*4^2)]/4} - [(pi*5^2)/4]