a boat weighs 1500 more than its motor and 1900 more than its trailer. Together the boat and motor weigh 5 times as much as the trailer. How much does the boat weigh?
B = boat weight
B-1500 = motor weight
and B-1900 = trailer weight
B + motor weight = 5* trailer weight
substitute into the last equation
B + (B-1500) = 5* (B-1900)
B+ B-1500= 5B-9500
set the unknown to one side of the equation
-1500 +9500 = 5B -2B
8000 = 3B
8000/3 = B
2666.67 = B