Hey i'm kinda i keep on getting 0.8 but i'm solving it on something ellse and getting -1 [12-[x+3]=10] btw that's the question

Long division setup showing an incomplete calculation. 12 is in the divisor, 6839 is in the dividend, and 5 hundreds and 6 tens is written in the quotient. 6000 is subtracted from 6839 to give 839. an unknown value represented by a box is being subtracted from 839. what number should be placed in the box to complete the division calculation?