a: =>3x-15-2x+6=51
=>x-9=51
=>x=60
b: =>432-2x+22+3x-15=200
=>x+439=200
=>x=-239
c: =>3x+17-4x+13=0
=>30-x=0
=>x=30
d: =>x-3-3x+6=-11-21=-32
=>-2x+3=-32
=>-2x=-35
=>x=35/2
\(3\cdot\left(x-5\right)-2\cdot\left(x-3\right)=51\)
\(\Rightarrow3x-15-2x+6=51\)
\(\Rightarrow x-9=51\)
\(\Rightarrow x=51+9\)
\(\Rightarrow x=60\)
b) \(432-2\cdot\left(x-11\right)+3\cdot\left(x-5\right)=200\)
\(\Rightarrow432-2x+22+3x-15=200\)
\(\Rightarrow x+439=200\)
\(\Rightarrow x=200-439\)
\(\Rightarrow x=-239\)
c) \(3x+17=4x-13\)
\(\Rightarrow4x-3x=17+13\)
\(\Rightarrow x=30\)
d) \(\left(x-3\right)+21=3\cdot\left(x-2\right)-11\)
\(\Rightarrow x-3+21=3x-6-11\)
\(\Rightarrow x+18=3x-17\)
\(\Rightarrow3x-x=18+17\)
\(\Rightarrow2x=35\)
\(\Rightarrow x=\dfrac{35}{2}\)