Mohon bantuan nya!! Tolong jawab beserta cara nya

diketahui :
panjang = 5x-1
lebar = 3x+5
keliling = 40
ditanya :
luas?
jawab :
keliling persegi panjang = 2(p+l)
40 = 2(5x-1+(3x+5))
40 = 2(8x+4)
20 = 8x+4
16 = 8x
2 = x
*panjang = 5x-1 = 5.2-1 = 9
*lebar = 3x+5 = 3.2+5 = 11
Luas = panjang x lebar
=9 x 11
=99 m²

Langsung aja y

K = 2(p+l)
40 = 2(5x-1 + 3x+5)
20 = 8x + 4
8x = 20 - 4
x = 16 : 8
x = 2

p = 5x - 1 = 5(2) - 1 = 9 m
l = 3x + 5 = 3(2) + 5 = 11 m

L = p × l
L = 9 × 11
L = 99 m²

Jawabannya D