Question 15139
Let x = width of the rectangle
x+3 = length of the rectangle

Area = L*W 

x(x+3)= 70
{{{x^2 + 3x-70=0}}}
{{{(x+10)(x-7)= 0}}}
x=-10 
Reject, since width of a rectangle can't be negative


x= 7 cm Width
x+ 3 = 10 cm Length


Check:  
Area= 7*10= 70 sq.cm.


R^2 at SCC