John buys 8 packs of cookies at the grocery store. The cookies are on sale for 50 cents off per pack. He spends $20. Which equation can be used to find the original cost of a box of cookies, c?(1 point) Responses 8(c 0.50)=20 8 times open paren c plus 0 point 5 0 close paren is equal to 20 8c−0.50=20 8 c minus 0 point 5 0 is equal to 20 8(c−0.50)=20 8 times open paren c minus 0 point 5 0 close paren is equal to 20 8−0.50c=20