Answer
Combined Weight for Billy and Mark = (Billy's weight) + (Mark's weight)
Combined weight = 70 + 50
Combined weight = 120 kilograms
Step-by-step explanation
An expression for their combined weight is the sum of their weights.
Combined Weight for Billy and Mark = (Billy's weight) + (Mark's weight)
Combined weight = 70 + 50
Combined weight = 120 kilograms
Hope this Helps!!!