6: -8+4V
8: -9-15V OR -9+(-)15V
10:-17+33V
Answer:
First, we have rounded numbers A and B, and we know that:
A + B = 11000
A - B = 3000
Now we can solve this system of equations as:
Isolating one variable in one of the equations, i will choose A in the second equation:
A = 3000 + B.
Now we can replace this into the other equation:
3000 + B + B = 11000
2*B = 11000 - 3000 = 8000
B = 8000/2 = 4000
and:
A - 4000 = 3000
A = 3000 + 4000 = 7000.
But remember that our original numbers are not exactly whole numbers, they are rounded up, so we could write them as:
A = 6999.8 (that would be rounded up to 7000)
B = 3999.7 (that would be rounded up to 4000)
The sum is:
A + B = 10999.5 (notice that this would be rounded up to 11000)
A - B = 3000.1 (this would be rounded down to 3000)
