diketahui sistem persamaan : 2x + y = p+2 x - y = p-1 x + y = 6 untuk bilangan bulat p, nilai x+y+p adalah...

2x + y = p + 2
x + y = 6
___________ -
x = p - 4

x - y = p - 1
x + y = 6
_________ +
2x = p + 5
2(p - 4) = p + 5
2p - 8 = p + 5
2p - p = 8 + 5
p = 13

x = p - 4
x = 13-4
x = 9

x + y = 6
9 + y = 6
y = 6 - 9
y = -3

p = 13
x = 9
y = -3

x + y + p = 9 + (-3) + 13
= 19

Maaf kalau salah^^