+130575 Here's the graphical solution to this problem.......https://www.desmos.com/calculator/vz1jfyne4s
The corner points of the feasible region occur at (3,6) (4,2) and (9,9)
And any max or min occurs at a corner point ... in this case, (9, 9) maximizes f(x,y) = 9x + 5y ......(4, 2) would minimize this, given the constraints.....
+130575 |-8x+5|≥ 10
We can solve two equations here, the first is
-8x + 5 ≥ 10 subtract 5 from both sides
-8x ≥ 5 divide by -8 and reverse the inequality sign
x ≤ -5/8
The second equation is
- (-8x + 5) ≥ 10
8x - 5 ≥ 10 add 5 to both sides
8x ≥ 15 divide both sides by 8
x ≥ 15/8
So the solutions are (-∞, -5/8] U [15/8, ∞ )
Here's a graph of the solutions......https://www.desmos.com/calculator/qzczn5jqny
