F = 9/5 C + 32°
C=(F-32°)*5/9
77° ≤ F ≤ 86°
=> 77°-32° ≤ F-32° ≤ 86° -32°
=> 45° ≤ F-32° ≤ 54°
=>45o*5/9 ≤ (F-32°) *5/9 ≤ 54°*5/9
=>25° ≤ C ≤ 30°.

x-1>-x+7
=>2x>8 => x>4.

x>7 and 7>4 => x>7>4 => x>4.
If x>7 n x cannot be less than 6.
If x=11 n x>7 and x>9.
If x=11 n x>7 and x<14.

Since region involves 1^st quadrant so x≥0, y≥0.
Two points on line are (0,6) and (3,0).
(y-6)/(0-6) = (x-0)/(3-0)
=>(y-6)/(-6) = x/3
=>y-6=-2x => 2x+y=6
2x+y≤6 since (0,0) should also satisfy.
So, 2x+y≤6, x≥0, y≥0.

Average is at least 30 marks.
Let x be marks in 3^rd test.
Average = (20+25+x)/3 ≥30
=>45+x≥90 => x≥90-45 => x≥45.
Minimum marks in 3^rd test should be 45.

Since it has highest power of x ?1? and has inequality sign so, it is called linear inequality.
It is not numerical inequality as it does not have numbers on both sides of inequality.
It does not have two inequality signs so it is not double inequality.

If we multiply by negative number on both sides of inequality n sign of inequality will change i.e. if x>7 n (-1) x < (-1)7 => -x<-7.

3x-6 ≥ 0 => x ≥ 2.
(0,0) does not satisfy te equation so region is right side of x=2 with complete line x=2 due to presence of equality sign along with inequality sign.

10x?50
Dividing by 10 on both sides, x ? (50/10) => x?5
Since x is a whole number so x = 0,1,2,3,4,5.

Since it has equality sign along with inequality sign so it is a slack inequality not strict inequality.