tolong pake Cara matematika

3 .
L = ½ × 30 × 50
L = 750 cm

4.
K = 2p + 2l
K = 2(2x-1) + 2(x + 2)
k= 4x - 2 + 2x +4
34= 4x - 2x -2 +4
34=2x-2
2x = 32
x= 32/2= 16

Panjang = (2x - 1) = 2(16)-1= 31 cm
lebar = (x + 2) = 16 + 2 = 18cm

5. L¹ = 4 × 5 = 20
L² = 6 × 7 = 42
jadi 42-20=22 cm