Answer:
61/4 kg (the larger box's weight)
25/4 kg(the small box's weight)
Step-by-step explanation:
You can set x = weight of large box and y = weight of small box. Since they tell you 3 large boxes and 5 small boxes has a total weight of 77 kg you can create an equation of 3x+5y = 77. They also tell you that 6 large boxes and 2 small boxes has a total weight of 104 kg so you can write 6x+2y = 104.
Now you have two equations and two unknowns so you can solve using systems of equations.
3x+5y=77
6x+2y=104
You can see that you can easily multiply the first equation by 2 to get a 6x and leave the second equation as is since it also has a 6x so you can subtract the two equations to eventually only have one variable.
6x+10y = 154
-(6x+2y=104)
___________
8y = 50
y = 50/8 = 25/4 kg
Now you solved for the smaller box's weight and you can plug it into any of the two equations above to solve for x.
6x+2(25/4) = 104
6x+25/2=104
6x+25/2 = 208/2
6x = 183/2
x = 183/12 = 61/4 kg (the larger box's weight)
