What is the width for 60 square inches by 12 inches?

There is NO width!!!

You misunderstand 60 sq. ins. has a width.!!!!

60sq. ins X 12 ins = 720 cu.ins. The shape is a CUBOID. with a width 'hidden' in the 60 sq. ins.

NB

Remember length(ins) X width(ins) = area(sq.ins).

You are given 60 sq.is, which is the AREA, without knowing the length or width .