In order to figure this out, we can set up a proportion and simplify using cross multiplication.
\(\frac{units_1}{cost _{1} } =\frac{units_2}{cost _{2} } \\ \\ \frac{6}{5.34} = \frac{1}{x} \\ \\ 6*x=5.34*1 \\ \\ 6x=5.34 \\ \\ x=0.89\)
One grapefruit costs 89 cents.
