Polly spends 20*7 =<<20*7=140>>140 minutes cooking breakfast.
She spends 5*7= <<5*7=35>>35 minutes cooking lunch.
She spends (10*4)+(30*3)= <<10*4+30*3=130>>130 minutes cooking dinner.
Therefore, she spends 140+35+130=<<140+35+130=305>>305 minutes cooking this week.
#### 305