Let width of each rectangle = x and the length = y. Area of 1 rectangle = 288/9 = 32. Then we have the following system of equations;
xy = 32
3y (x + y) = 288
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Expanding the second equation:-
3xy + 3y^2 = 288
Substitute xy = 32 in the above equation:-
3*32 + 3y^2 = 288
3y^2 = 288 - 96 = 192
y^2 = 192/3 = 64
y = 8 , So x = 32/y = 32/8 = 4
The perimeter = 2 (3*8) + 2( 4 + 8)
= 48 + 24
= 72 cm Answer