Amigo Mobility, which manufactures battery-powered mobility scooters, has $680,000 to invest. The company is considering three different battery projects that will yield the following rates of return: Deep cycle = 13% Wet/flooded = 40% Lithium ion = 23% The initial investment required for each project is $180,000, $100,000, and $400,000, respectively. If Amigos invests in all three projects, what will be its overall rate of return? The rate of return is %.