We take the value of F in the inequality by taking the inequalities in group. Let the first group be:
(1) -20 ≤ 59(F - 32)
Then, the second group would be,
(2) 59(F - 32) ≤ - 15
Calculating for the values of F,
(1) -20 ≤ 59F - 1888
1888 - 20 ≤ 59F
1868 ≤ 59F
F ≥ 31.66
(2) (59)(F - 32) ≤ - 15
59F - 1888 ≤ -15
59F ≤ 1873
F ≤ 31.75
The values of F are therefore,
31.66 ≤ F ≤ 31.75
This would be the identity property of addition telling us that any number added to zero is that number (i.e. 6 added to zero is still 6)
