Answer:
the answer I got is 8 but I'm not sure if it's right though
Step-by-step explanation:
step1) you count each side of the last layer E.g the first line :7+5+5=17 then, 5+7+6=18 and 7+8+3=18
step2) from this u can c tat both sides(7,8,3) and (5,7,6) have the same amount of number which is 18
step3) so from this , what I'm doing is basically assuming tat the line (7,5,5) and (3,?,6) will add up to the same number which is 17
step4) thus we use 17 - 6 - 3 =8
