You Just want to get Fahrenheit alone on one side of the equal sign. Your teacher forgot to use parenthesis. The correct equation for Celsius to Fahrenheit is:
Which will give you a completely different answer.... 
****
We will solve it using what is given:
C = (5/9)F - 32
C + 32 = (5/9)F
9(C + 32) = 5F
(9/5)(C + 32) = F
** If they mark you wrong, and try to say the answer is F = (9/5)C + 32 then they shouldn't be teaching math, and you should point out the fact there are no parenthesis around the F - 32 in the given formula.
2.83 if rounded. 2.82842712475 would be the actual.
Hope this helped!
Answer:
See attachment
Step-by-step explanation:
We want to graph the system
2x+y=8
-x+2y=6
Let us rewrite the lines in slope intercept form:
y=-2x+8

The first line has a slope of -2 and a y-intercept of 8
The second line has a slope of 1/2 and a y-intercept of 3
We can no graph the lines as shown in the attachment.