 
<translate> Da farko ka lissafa jimillar lokacin da Gretchen take zama a teburinta: awa 6 * minti 60 a awa ɗaya = minti 360. Sai ka raba wannan adadin da minti 90 don ka san yawan lokacin da Gretchen take hutu don tafiya: Minti 360 / minti 90 / hutu = hutu 4. Sai ka ninka adadin lokacin da Gretchen take hutawa da tsawon lokacin da take hutawa don ka san tsawon lokacin da Gretchen take tafiya: 4 hutawa * minti 10 / hutawa = minti 40. Amsar ita ce 40. <eng> First find the total number of minutes Gretchen spends sitting at her desk: 6 hours * 60 minutes / hour = 360 minutes. Then divide this amount by 90 minutes to find how many walking breaks Gretchen takes: 360 minutes / 90 minutes / break = 4 breaks. Then multiply the number of breaks by the length of each break to find how long Gretchen spends walking: 4 breaks * 10 minutes / break = 40 minutes. So, the answer is 40. 