Answer:
the correct solution has been explained
Step-by-step explanation:
Jackson,s reasoning is incorrect because it should be 8 ones and not 8 tens that would give 64

Moreover, 
as 
whereas
= 8
clearly, both quantities are different
S/4-6.8=-9.8
S/4= -9.8+6.8
S/4= -3
S=-3*4
S= -12