Do the equations y = - 5/4x + 2 and 10x + 8y = 16 define the same line?

In order to solve this you could take the two equations and put them in the same format. 
The first equation:          y = - 5/4x + 2
The second equation:    10x + 8y = 16  For this one, you could take the 16                                                                 and subtract it, and then take the 8y                                                               and subtract it.                                                                        10x - 16 = -8y   Divide both sides by -8                                                         -10/8x + 2 = y    Simplify
                                    -5/4x + 2 = y
Now you can compare the two equations:
Equation 1: y = - 5/4x + 2
Equation 2: y = - 5/4x + 2 

You can obviousley see that they are in fact the same. 

To draw a histogram, you need two axes. The horizontal axis is the day and the vertical axis is the number of text messages. For the first day, there are 20 text messages. This is represented by a bar starting from the horizontal axis labeled Day 1 going up to the point where the vertical axis indicates 20 text messages. This is done for the rest of the data. Afterwards, a line is drawn from the vertex of the axes connected to the top of the first bar. Then from the top of the first bar, a line connects it to the top of the next bar. This is done for all the bars before producing a histogram.