Let L and S represent the weights of large and small boxes, respectively. The problem statement gives rise to two equations: .. 7L +9S = 273 .. 5L +3S = 141
You can solve these equations various ways. Using "elimination", we can multiply the second equation by 3 and subtract the first equation. .. 3(5L +3S) -(7L +9S) = 3(141) -(273) .. 8L = 150 .. L = 150/8 = 18.75 Then we can substitute into either equation to find S. Let's use the second one. .. 5*18.75 +3S = 141 .. S = (141 -93.75)/3 = 15.75
A large box weighs 18.75 kg; a small box weighs 15.75 kg.