positive number times negative number is negative number "(+)(-) = (-)".
[tex]1\dfrac{1}{2}\cdot\left(-1\dfrac{1}{4}\right)=-\left(1\dfrac{1}{2}\cdot1\dfrac{1}{4}\right)[/tex]
we change the mixed numbers to the improper fractions
[tex]=-\left(\dfrac{1\cdot2+1}{2}\cdot\dfrac{1\cdot4+1}{4}\right)=-\left(\dfrac{3}{2}\cdot\dfrac{5}{4}\right)=-\dfrac{3\cdot5}{2\cdot4}=-\dfrac{15}{8}=-1\dfrac{7}{8}[/tex]
