$\backslash$table$[[$Hour$,$Machine $1,$Machine $2,$Machine $3],[1,,,$RED$],[2,$BLUE,RED,$],[3,$BLUE,,$],[4,$BLUE,,$],[5,,,$BLUE$],[6,,$RED,$],[7,,$RED,$],[8,,,]]$

Refer to the figure above. Green will first be processed on machine $2$ for $1$ hour, then on machine $1$ for $2$ hours, and finally on machine $3$ for $1$ hour. Green is due at the end of hours $8.$ Red and Blue are fixed, you may not move them. Using Backward scheduling:

$$ You will start Green on Machine $2$ in hour $5$

No feasible schedule is possible.

You will finish Green in Hour $7$

You will start Green on Machine $2$ in hour $1$