Respuesta :

Answer:

x=3cm

Step-by-step explanation:

We have three figures.A triangle(8 by X+3).In it we have another triangle(4 by x)and a trapesium

thus that means the area of the trapesium+area of small triangle=area of big triangle.

1)Area=1/2lengthxwidth. =1/2×8×(x+3)

=4(x+3)

=4x+12cm³

2)Area=1/2lengthxwidth. =1/2×4×x

=2x

3)area=1/2(a+b)h

=1/2(x+3+x)×4

=1/2×4(2x+3). (area of trapesium)

=2(2x+3)

=4x+6cm³

thus:

2x+4x+6=4x+12 put like terms together

2x+4x-4x=12-6

2x=6 divide both sides by 2

x=3cm