B is a times b
C is  also a times b
sorry im stuck on the rest
        
             
        
        
        
Here,
let width(b)be x then,
length (l)=9cm+x
area =112 sq cm
now,
area of rectangle=l*b
 or, 112=(9+x)x
 or, 112=9x+x^2
 or, 0=x^2+9x-112
 or, 0=x^2+(16-7)x-112
 or, 0=x^2+16x-7x-112
 or, 0=x(x+16)-7(x+16)
 or, 0=(x-7)(x+16)
either,
 0=x-7
 or,7=x
 x=7cm
 Or, 
 0=x+16
 or, -16=x 
 x= -16[impossible,as distance is never negative] so,
x=7cm 
therefore,length = 7cm + 9 cm = 16cm and width = 7cm. 
;)