Hi Lujain
Small box weighs 6.5 kgs
Large box weight 18.75 kegs
You can use a system of equations to solve your problem with elimination or substitution
Let l = large box
Let s = small box
According to the information given
2l + 3s = 57
6l + 5s = 145
If you multiply the first equation by -3 you can eliminate l when you combine it with the second equation
-3(2l + 3s = 57) becomes
-6l - 9s = -171
Now combine this with the second equation
-6l - 9s = -171
6l + 5s = 145
We have
-4s = -26
s = 6.5
Use this value in the original equation to solve for l
2l + 3(6.5) = 57
2l + 19.5 = 57
2l = 57 - 19.5
2l = 37.5
l = 18.75
Checking in the second equation
6(18.75) + 5(6.5) = 145
112.5 + 32.5 = 145
I hope this helps.