D and E are points on side AB and AC of ΔABC. DE is parallel to BC. If AD:DB = 2:5 and area of ΔABC is 98 cm sq, what is the area (in sq cm) of quadrilateral BDEC?
The numbers x, y, z are respectively proportional to 2, 3, 5 and the sum of x, y and z is 80. If the number z is given by the equation z = ax-8, then a is