Greg = 80
Dolores = 75% of Greg
Robert = 25% of Dolores + Greg
Dolores: x/80 = 75/100
Cross multiply
6000 divide by 100 is 60
Robert: 60 + 80 = 140
x/140 = 25/100
Cross multiply
3500 divde by 100 is 35
80 + 60 + 35 = 175
175 clients
*This is sort of embarrassing, but I'm not sure if "as many" means multiply it 60 by 80. But I chose not to multiply because it makes more sense.
Hopes this helps.