What is the final amount if 705 is decreased by 19% followed by a 10% increase? Give your answer rounded to 2 DP.

628.15

Step-by-step explanation:

When the amount is decreased by 19%, it is effectively multiplied by (1 -19%) = 0.81. When it is increased by 10%, it is effectively multiplied by (1+10%) = 1.10. These two changes result in the value ...

 705×0.81×1.10 = 628.155

One possible equation could be y = -2x^2 - 3.

The equation that is given would be in the shape of an upside down parabola. It would have a maximum (vertex) at (0, -3). 

The point (0, -3) would also be the y-intercept of the graph.

You could change the -2 to any other negative number and the equation would work in your problem.