The 3rd answer is wrong, the answer is 19.
The 5th answer is wrong, the answer is -9.
The 7th answer is wrong, the answer is 8.
The 11th answer is wrong, the answer is 2.
The 12th answer is wrong, the answer is 10.
Hope I could help :)
That would be 0.24(0.4). First, estimate the result: 0.24 is about 1/4, and (1/4)(0.4) is about 0.1.
0.24(0.4) = 0.096 (which agrees with the estimated answer, 0.1).
It would be none because the same would be the reciprocal which would be (-7, -8.75)