Question 465918
Start with the slope-intercept form:
.
{{{y = mx + b}}}
.
In which m is the slope and b is the value on the y-axis where the graph crosses the y-axis. You are told that the slope is {{{-7/2}}}. This value can be substituted for m in the slope-intercept form to get:
.
{{{y = (-7/2)x + b}}}
.
You are also told that the point (-2,5) is on the graph. All the points on the graph have to satisfy the slope-intercept form.  Therefore, when x is -2 and y is +5, they satisfy the slope-intercept equation.  So we can substitute -2 for x and +5 for y and know that the equation must be true. When we make those substitutions, the equation becomes:
.
{{{5 = (-7/2)*(-2) + b}}}
.
Do the multiplication of the first term on the right side of the equal sign to get:
.
{{{5 = 7 + b}}}
.
Solve for b by subtracting 7 from both sides to find that:
.
{{{5 - 7 = +b}}}
.
which simplifies to:
.
{{{b = -2}}}
.
At this point we know that the slope is -7/2 and -2 is the value on the y-axis where the graph crosses. Therefore, substituting these two values (m and b) into the slope-intercept equation of a line results in the equation becoming:
.
{{{y = (-7/2)*x -2}}}
.
And this is the answer. It is an equation for the line having a slope of -7/2 and also having the point (-2,5) on the line.  
.
Hope this helps you to understand how to work with one of the forms of an equation that describes a specific straight line line on a graph.