berapa cm² selisih luas bangun (a) dan bangun (b) diatas?

Luas bangun a
L1 = s² = 3 × 3 = 9 cm²
L2 = p × l = 10 × 4 = 40 cm²
L ttl = 9 + 40 = 49 cm²

Luas bangun b
L1 = p × l = 12 × 8 = 96 cm²
L2 = ½ × a × t = ½ × 8 × 3 = 12 cm²
Lttl = 96 + 12 = 108 cm²

selisih luas a dan b
= 108 cm² - 49 cm²
= 59 cm²

B₁ = (3cm x 3cm) + (4cm +  10cm)
     = 9cm² + 40cm²
     = 49cm²

B₂ = (8cm x 12cm) + (8cm x 3cm : 2)
     = 96cm² + 12cm²
     = 108cm²

S (B₁ & B₂) = 108cm² - 49cm²
                   = 59cm²

semoga membantu !
maaf ya kalo kurang jelas !