The surface area can be calculate using the formula:
S.A =2lw+2lh+2hw
where l is the length, w is the width and h is the height
From the question, l=6 w = 4 and h =2
Subatitute the values and evaluate
S.A = 2(6)(4)+ 2(6)(2) + 2(2)(4)
= 48 + 24 + 16
= 88 square inches