Keliling Sebuah persegi panjang 64cm dan perbandingan panjang dan lebarnya 5:3 luas persegi panjang adalah

P = 5x
L = 3x
maka:
K = 2(P + L)
K = 2(5x + 3x)
64 = 2 (8x)
64 = 16x
x = 64/16
x = 4 cm

P = 5x = 5*4 = 20 cm
L = 3x = 3*4 = 12 cm

Luas = P x L = 20 x 12 = 240 cm^2

P : l = 5 : 3

K = 2p + 2l

32 = p + l

Jumlah perbandingan = 5 + 3 = 8

jdi

P = 5/8 × 32

= 5 × 4

= 20 cm


l = 3/8 × 32

= 3 × 4

= 12 cm


jdi luasnya

L = P × l

= 20 cm × 12 cm

= 240 cm^2