Hello!
As this exercise informs the approximate heights, you can consider just this value (don't need to write two heights in this case).
To make this chart, I used the heigths:
• Mercedario: 6770m
,• Misti, Volcán: 5820m
,• Pular: 6230m
,• Sajama: 6520m
,• Talima: 5220m
Look at the chart below: