Ineed with this question 2 -3/4k=1/8k+9

Simplify. (-2)^-3 a. -8 b. -1/8 c. 1/8 d. 8

Jake bakes and sell apple pies. he sells each pie for $5.75 . the materials to make the pies cost $40. the boxes jake puts the pies in cost & 12.50 total. how many pies does jake need to sell to earn a profit of $50

Ithink i know it but i want to be sure so can you me out ?