Respuesta :

Answer:

15

Step-by-step explanation:

Answer:

The value of x is 28cm.

Step-by-step explanation:

Area of a trapezium = ½h(a + b)

240 = ½×12×(12 + x)

240 = 6(12 + x)

240 = 72 + 6 x

240 - 72 = 6x

168 = 6x

168/6 = x

28 = x