The answer is D because a function means for every input you get exactly one output so
for every x you get one y
in D there is a coordinate (5,2) meaning that if you put in 5 for x you get 2 for y
but the new ordered pair also has 5 for x but has a difarent y value. this violates the definition of a funciton
We can put it into one step by multiplying the cost by 1.07 which basically takes into account the old cost of the jacket and the tax
the expression is
original amount * decimal multiplier (1.07) = new amount