a: \(\Leftrightarrow\left[\left(999-3n\right)\cdot60\right]\cdot24=360\)
=>60(999-30n)=15
=>999-30n=1/4
=>30n=998,75
hay n=799/24
b: \(\Leftrightarrow\left(2n-124\right):5=32-9\cdot2=14\)
=>2n-124=70
=>2n=194
=>n=97
c: =>4n-[9000-2642-4654+2342]=34
=>4n=6080
=>n=1520