**By Analyzing ROW 1 and ROW 3**

we can write equations as

**3x+y=45** (from ROW 1)

**x+3y=55**(from ROW 3)

we get **x=10** and **y=15**

Now from ROW 2 we can write

**x+y+2z=39**

=> 10+15+2z=39

=> 2z=39-25

=> 2z=14

=>z=7

**HENCE THE VALUE OF BOTTOM ROW IS**

7+7+10+7=**31(ANSWER)**