Tìm x

Tìm x 
a,210–5x =200. 
b,210 : x–10=20
c, 210–5(x–11)=200
d, (2x+1) :7=2^2 +3^2
e, 450:[41–(2x–5)]=3^2×5
f, (5x–9)×7+3=80