Why calculate return with IRR?

Hello, I am wondering why in this question, when I receive 60 in period 1, 60 in period 2 and 326.74 in period 3, I need to calculate the return with the IRR formula (investment costs are 1090). Why can't I calculate (60+60+326.74)/1090 -1? Is it because the IRR assumes reinvestment of these cash flows?

https://imgur.com/a/LNv8pjo

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thanks!