How do you solve 9 - x = 10 using algebraic operations?

Andrea went to the store to buy sweater that was on sale for 40% off the original price it was then put on clearance an additional 25% off the sale price she also use a coupon that saved her an additional five dollars and j did not spend more than $7.60 for the sweater what are the possible values for the original price of the sweater?

Cassie is traveling 675 miles today to visit her brother and his family. so far, she has stopped for gas three times. at the first stop, she put in 7.1 gallons of gas and paid $23.79. at her second stop, she put in 5.8 gallons of gas and paid $19.08. and, at the third stop, 6.6 gallons and paid $20.39. at which stop did casey pay the most for gas?

Jackie purchased 3 bottles of water and 2 cups of coffee for the family for $7.35. ryan bought 4 bottles of water and 1 cup of coffee for his family for 7.15. how much does each bottle of water cost? how much does each cup of coffee cost?