I think it’s A, B, C or D
If there are 3 shelves 0.3m wide and there is a 0.05m gap on both sides between the shelves and the wall, all you have to do is add.
0.3 + 0.3 + 0.3 + 0.05 + 0.05 which is equal to 1.00 or C. 1
ABC is an equivalent triangle, all sides are equal
So AB = BC = AC
Plug in any two sides to find x
4x - 10 = 3x + 2
x = 12
Answer
x = 12
