Where you see l plug in 2.4, where you see w plug in 1.3 and where you see h plug in 0.8
2 times 2.4
4 times 1.3
2 times 0.8
you can rewrite this like this
2*2.4 + 4*1.3 + 2*0.8
order of operations says that you multiply first then add. When you multiply you get
4.8+5.2+1.6
then just add the remaining numbers
11.6