The length of a rectangularexceeditsbreath by9cm.if length&breadth increase by3cmtheofnewrectangle84cmwhat l&b

Answer 1

Let 'l' cm be length.... 'b' cm be the breadth
l = b + 9...(1)

Since your question is unclear and if you mean perimeter of new rectangle then:
2(l+3+b+3) = 84
2b+15 =42
2b = 27
b=13.5 cm
l= 22.5 cm
___________ _____________ __________ ______
I
f u mean new area is 84 cm^2
(l+3)(b+3) = (b+12)(b+3) = 84
b^2 + 15b + 36 = 84
b^2 + 15b - 48 = 0

b = 2.71 cm excluding the other root which is -ve
l = 11.71 cm

Answer 2

let length be a, breadth be b
we have
a = b + 9
(a+3) + (b + 3) = 84
=> a = 43.5, b = 34.5