Answer:
6
Step-by-step explanation:
2+r=4
4x4=16
16+r=18
18-12=6
r + 4(2 + r) - 12 =
2 + 4(2 + 2) - 12 =
2 + 4(4) - 12 =
2 + 16 - 12 =
18 - 12 =
= 6
