Yasmin bought 3 1/2 pounds of ground beef, we can express the amount that she bought as a fraction like this:
[tex]3\frac{1}{2}=\frac{3\times2+1}{2}=\frac{6+1}{2}=\frac{7}{2}[/tex]Since she bought it for $11.2, if we divide the cost by the amount that she purchased, we get the cost per pound, like this:
[tex]\frac{11.2}{\frac{7}{2}}[/tex]To divide by a fraction, we just have to invert its numerator and denominator:
[tex]\frac{11.2}{\frac{7}{2}}=11.2\times\frac{2}{7}=\frac{22.4}{7}=3.2[/tex]Then, the cost per pound equals $3.2