tolong bantu saya nomor 1,2 paki jalannya

a) L = ½ × ( a + b ) × t
L = ½ × ( 8 + 4 ) × 5
L = ½ × 12 × 5
L = 30 cm²

b) L = ½ × ( a + b ) × t
72 = ½ × ( a + 10) × 8
72 = ( a + 10) × 4
a + 10 = 72 ÷ 4
a + 10 = 18
a = 18 - 10
a = 8 cm