It seems that the total area is 60 square units (6x10) from the long base of the trapezoid (6).
To find a trapezoid, add both bases and divide it by two (6+4)/2 giving 5
Now multiply by height to get 25 square units per trapezoid
Multiply by two for two trapezoids
Of the 60 square units of area our trapezoids take 50 square units.
Now we know in together the two triangles are 10 square units.
Divide by two and now we know each triangle is
5 square units each