Question

\[c \le ax+b \le d\]
for x, if a < 0

Answer 1

\[c \le ax+b \le d\]

for x, if a < 0

Answer 2

\[
c≤ax+b≤d \\
c -b \le a x \le d-b\\
\frac {c-b}a \ge x \ge \frac {d-b} a
\]