Answer:
61 cm for each book shelf.
Step-by-step explanation:
First it gives you the width of the boxes so you add them together
132 + 108 + 94 = 334
so 334 cm has already been used out of 456 cm.
Next you will 456 - 334 = 122 cm left over
if they are building 2 book cases you with take what cm's you have left and divide it by 2
122 / 2 = 61
So that means each book case will be 61 cm's wide