Given:
The average price of gas Johannesburg is about 19.24 ZAR per liter.
a) The equivalent amount in US dollars is,
[tex]\begin{gathered} 1\text{ USD=}15.91\text{ ZAR} \\ 19.24\text{ ZAR=}\frac{19.24}{15.91}\text{ USD=1.21 USD} \end{gathered}[/tex]b) The rate in US dollars per gallon is,
[tex]\begin{gathered} 1\text{ litre=}\frac{1}{3.785}gallon \\ 1\text{ ZAR per litre=0.237704933 USD per gallon} \\ 19.24\text{ ZAR per litre=4.57344 USD per gallon} \end{gathered}[/tex]