Question

Four crates contain cereals. When 9 kg was taken out of each box, then all together left as much as was in each. How many kilograms of cereal were in each box?

Answer 1

we make the equation to the problem:

$4(x-9)=x, \\4x-36=x,\\ 3x=36\\ x=12$

Аnswer: Еach box had 12 kg of cereal.