bantu kerja kakak ,susah sekali

sisi segitiga a, b, dan c. a yang terpanjang, c yang terpendek.
a + b + c = 19

a = 2c
a = b + c - 3 
 
masukkan a = 2c2c = b + c - 3

c = b - 3
a + b + c = 19; masukkan a = 2c2c + b + c = 19

masukkan c = b - 32 (b - 3) + b + (b - 3) = 192b - 6 + b + b - 3 = 194b - 9 = 194b = 28b = 7 cm

c = b - 3c = 7 - 3c = 4 cm
a = 2ca = 2 x 4a = 8 cm

jadi sisinya 4 & 8