S=(a+b)×h÷2

= 10+2× 12÷2

= 12× 12÷2

= 144÷2

=72

The triangle above

S=ah÷2

=3×4÷2

=6

Lower trapezoid

S=(a+b)×h÷2

=(4+6)×4÷2

=20

72-6-20=46

If you are satisfied, please adopt it. Thank you for your cooperation! ~