hello :
let : y the length and : x the width
y = 2x +3.....(1)
xy = 77 .....(2)
by (1) subsct : y i n (2)
x(2x+3) = 77
2x²+3x -77 = 0
the descrimnent : b²-4ac ... a =2 b= 3 c = -77
3²-4(2)(-77) = 625 = 25²
x1 = (-3-25)/4 negatif refused
x2 = (-3+25)/4 =22/4 = 11/2
x= 5.5
y = 2(5.5) +3 =14
