we need to read the Q properly

its written 3 pyramid width on the longer side 2 cubewidth onthe shorter side

8 pyramid width 6 cubewidth (its not given on the shorter side )

8*10 6x(let cubewidth x)

x-80/6 13.3333

so 2x 13.333*2 26.66 (approx)

i think this is correct