Given that Mandy Cart Contains :
5.1 pounds of Apples that cost $0.79 a Pound
From the above statement we can say that :
One Pound of Apples cost is 0.79 Dollar
5.1 Pounds of Apples cost = 5.1 × Cost of One Pound of Apples
5.1 Pounds of Apples cost = (5.1 × 0.79) Dollar = 4.029 Dollar
So the Cost of Apples Mandy Put in her Cart is 4.029 Dollar