Round 10
Let's imagine:
Guns are A
Feather is B
Pants are C
First
A + A + A = 30
3A = 10
A = 10
Second
BxA + B = 77
10B + B = 77
11B = 77
B = 7
Third
CxA + C = 22
10C + C = 22
11C = 22
C = 2
Final
A + CxB = 10 + 2x7 = 10 + 14 = 24
The solution is 24.