diketahui keliling persegi panjang 20m jika sisi panjangnya 5×3m dan sisi lainnya 3×-1

1)Rumus : K = 2(p + l )
20 = 2(5x + 3 + 3x - 1)
= 2(8x +2)
= 16x + 4
20 - 4 = 16x
16 = 16x
16 : 16 = x
1 = x
2) panjang = 5(1) + 3
= 5 + 3 = 8m
Lebar = 3(1) - 1
= 3 - 1 = 2m
3) luas = p × l
= 8m × 2m
= 16m2