Physics problem: how to do, thanks.?

Vo = RʟV / (Rʟ+Ri) where Vo is output under load, V is no load output, Rʟ is load resistor, Ri is internal Resistance
Vo = RʟIo
Io = V / (Rʟ+Ri)

2 = V / (20+Ri)
2.5 = V / (10+Ri)

2 eq in 2 unknowns
40 + 2Ri = V
25 + 2.5Ri = V
40 + 2Ri = 25 + 2.5Ri
15 = 0.5Ri
Ri = 30 Ω

check
V = 40 + 2Ri = 40+60 = 100 volts
V = 25 + 2.5Ri = 25+75 = 100 volts

Vo = RʟV / (Rʟ+Ri)
Vo = 20•100 / (30+20) = 200/5 = 40
Io  = Vo/Rʟ = 40/20 = 2 amps

Vo = 10•100 / (30+10) = 100/4 = 25Io  = Vo/Rʟ = 25/10 = 2.5 amps