The question requires us to form an algebraic expression in order to
calculate Dominic's weight, after telling us his weigh with respect to
his peers and the sum of their weights. Let D represent Dominic's
weight, R represent Ralph's weight and P represent Peter's weight. From
the given information, we can form:
2D = R
3D = P
P + R + D = 720
Now, we substitute values into the last equation:
3D + 2D + D = 720
6D = 720
D = 120
Dominic's weight is 120 pounds
