Answer:
We have the equations:
1.15x + 0.65y = 8.90
and
x − 3y = -15
First, let's write them in the slope-intercept form:
The first one will be:
y = -(1.15/0.65)*x + 8.90/0.65
The second:
y = (1/3)*x + 15/3 = (1/3)*x + 5.
then our system is:
y = -(1.15/0.65)*x + 8.90/0.65
y = (1/3)*x + 5.
To graph each line, you can just evaluate the line in two points (for x = 0 and x = 1, for example) and then locate those points in the coordinate axis, and then draw a line that connects them.
For example with the second line:
y(0) = (1/3)*0 + 5 = 5
then we have the point (0,5)
and
y(3) = (1/3)*3 + 5 = 8
Then we have the point (3,8)
With the first equation may be a little harder, as the coefficients are not whole numbers, we can rewrite it as:
y = (1.15/0.65)*x + 8.90/0.65 = (115/65)*x + (890/65)
Where i multiplied and divided by 100 the numerators and denominators in the right side, so now is easier to work with it.
The points you can use are:
y(0) = (115/65)*0 + (890/65) = 13.7
the point is (0, 13.7)
and:
y(1) = (115/65)*1 + (890/65) = 15.5
The point is (1, 15.5)
Below you can see the graphs of both functions:
blue: y = -(1.15/0.65)*x + 8.90/0.65
red: y = (1/3)*x + 5
