Tolong Ya!!! Pake Caranya Juga

Diketahui:
panjang:3x+5
lebar:2x-2
keliling:56 cm

ditanya:
luas?

jawab:
k=2(p+l)
56=2((3x+5)+(2x-2))
56=6x+10+4x-4
56=6x+4x+10-4
56=10x+6
10x=6-56
10x=-50
x=-10
kemudian di substitusikan:
panjang=3x+5
=3(-10)+5
=-30+5
=-25
lebar=2x-2
=2(-10)-2
=-20-2
=-22

luas=p×l
=-25×(-22)
=550 cm²




mohon maaf bila salah

K = 2 × ( p + l )
56 = 2 × { ( 3x + 5) + ( 2x - 2) }
56 ÷ 2 = 5x + 3
28 = 5x + 3
5x = 28 - 3
x = 5

maka
p = 3x + 5 = 3(5) + 5 = 15 + 5 = 20
l = 2x - 2 = 2(5) - 2 = 10 - 2 = 8

L = p × l
= 20 × 8
= 160 cm² ( B )