a) \(7.(-28) = (-49).4\)
\(\displaystyle {7 \over { - 49}} = {4 \over { - 28}};{{ - 28} \over { - 49}} = {4 \over 7};\)\(\,\displaystyle {7 \over 4} = {{ - 49} \over { - 28}};{{ - 49} \over 7} = {{ - 28} \over 4}.\)
b) \(0,36. 4,25 = 0,9. 1,7\)
\(\displaystyle {{0,36} \over {0,9}} = {{1,7} \over {4,25}};{{4,25} \over {0,9}} = {{1,7} \over {0,36}};\)\(\,\displaystyle {{0,36} \over {1,7}} = {{0,9} \over {4,25}};{{4,25} \over {1,7}} = {{0,9} \over {0,36}}.\)
