A 0.03-in-thick copper plate (k = 223 Btu/h · ft · °F) is sandwiched between two 0.15-in-t...

A 0.03-in-thick copper plate (k = 223 Btu/h · ft · °F) is sandwiched between two 0.15-in-thick epoxy boards (k = 0.15 Btu/h · ft · °F) that are 7 in × 9 in in size. Determine the effective thermal conductivity of the board along its 9-in-long side. What fraction of the heat conducted along that side is conducted through copper?