The person uses 5.4 calories in 1 minute.
To find how many minutes the person needs to use 170 calories, we can use the next proportion:
[tex]\frac{5.4\text{ calories}}{170\text{ calories}}=\frac{1\text{ minute}}{x\text{ minutes}}[/tex]Solving for x,
[tex]\begin{gathered} 5.4\cdot x=1\cdot170 \\ x=\frac{170}{5.4} \\ x\approx32\text{ minutes} \end{gathered}[/tex]A person must walk for at least 32 minutes in order to use at least 170 calories.
