PLEASE HELP WHAT (9+87k-l=12) solve for k and l please help me

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Aeolian processes,  pertain to  wind  activity in the study of  geology  and  weather  and specifically to the wind's ability to shape the surface of the  earth  (or other  planets). winds may  erode, transport, and deposit materials and are effective agents in regions with sparse  vegetation, a lack of soil moisture and a large supply of unconsolidated  sediments. although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as  deserts