Help me please tha is a practice but is I pass it will make me not fail math

What is the value of this expression when b= 5 6 (2b-4)

Simplify 5 square root of 7 end root plus 12 square root of 6 end root minus 10 square root of 7 end root minus 5 square root of 6 . (1 point) 5 square root of 14 end root minus 7 square root of 12 5 square root of 7 end root minus 7 square root of 6 7 square root of 12 end root minus 5 square root of 14 7 square root of 6 end root minus 5 square root of 7

Strawberries cause two hours per pound kate buys 5 pounds he gets 20% off discount on the total cost how much does kate pay for the strawberries