For the first blanks, move the decimal until you get 1.9 for A, 5.2 for B, 1.34 for C, and 9.5 for B. Then count how many places you moved the decimal. For A, you moved the decimal 5 places to the right, so the second black is -5. For B, you moved it 4 places to the left, so the second blank is 4.
