Residual distribution model, payout ratio

Hello, dear Friends!

Please, help me to solve this task from Financial Management book:

Welch Company is considering three independent projects, each of which requires a $5million investment. The estimated internal rate of return (IRR) and cost of capital for these projects are presented here:
Project H (high risk): Cost of capital = 16% IRR = 20%
Project M (medium risk): cost of capital = 12% IRR = 10%
Project L (low risk): Cost of capital = 8% IRR = 9%

Note that the projects’ cost of capital vary because the projects have different levels of risk. The Company’s optimal capital capital structure calls for 50% debt and 50% common equity. Welch expects to have net income of $7,287,500. If Welch establishes its dividends from the residual model, what will be its payout ratio?

I would appreciate your help!
Thank you! )