minta bantuannya gaess

Ini untuk jawaban nomor 1

1.
P - L = 7
P = 7 + L

2P + 2L = 78
2(7+L) + 2L = 78
14 + 2L + 2L = 78
4L = 64
L = 16 cm

P = 7 + 16 = 23 cm

Luas = 16 x 23 = 368 cm2

2.
2D + 3P = 8000
2D = 8000 - 3P
D = 4000 - 1,5P

3D + 7P = 14500
3(4000 - 1,5P) + 7P = 14500
12000 - 4,5P + 7P = 14500
2,5P = 2500
P = 1000

D= 4000 - (1,5 x 1000) = 4000 - 1500 = 2500

6D + 2P = 6 x 2500 + 2 x 1000 = 15000 + 2000 = 17000

Uang 20000 maka kembali => Rp 3000