Question

Dominic, Ralf and Peter have just eaten a HUGE Christmas meal. Dominic now weighs half as much as Ralph, and Peter weighs three times as much as Dominic. Together they weigh 720 pounds. How much does Dominic weigh?

Answer 1

To be able to calculate the problem above, we need to set up equations. We let,

D = Dominic weight
R = Ralph weight
P = Peter weight

We have three unknowns so we should set up three equations. We do as follows:

D = 0.5R
P = 3D
D+R+P = 720

Solving simultaneously we obtain,

D = 120
R = 240
P = 360

Therefore, Dominic weighs 120 mass units.