Please help with this ASAP, I rlly don’t understand if you just add or subtract.

15) What is the to number of years shown on the timeline?

The timeline chart is right in the picture and so is the question (extra points on this one)

Please help with this ASAP I rlly dont understand if you just add or subtract 15 What is the to number of years shown on the timeline The timeline chart is righ class=
Please help with this ASAP I rlly dont understand if you just add or subtract 15 What is the to number of years shown on the timeline The timeline chart is righ class=