GATE Civil Engineering (CE) 2020 Shift 1 Solved Paper

The data for an agricultural field for a specific month are given below:
Pan Evaporation $=100\mathit{m}\mathit{m}$
Effective Rainfall $=20\mathit{m}\mathit{m}$ (after deducting losses due to runoff and deep percolation)
Crop Coefficient $=0.4$
Irrigation Efficiency $=0.5$
The amount of irrigation water (in $\mathit{m}\mathit{m}$ ) to be applied to the field in that month, is