Question

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

Answer 1

For the answer to the question above, \
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

So the answer is 120 is the weight of Dominic