Tìm x

a,$\frac{x+5}{2016}+\frac{x+4}{2017}+\frac{x+3}{2018}=\frac{x+2016}{5}+\frac{x+2017}{4}+\frac{x+2018}{3}$ tìm x 
b,$(\frac{1}{4.9}+\frac{1}{9.14}+\frac{1}{14.19}+........+\frac{1}{44.49}).\frac{1-3-5-7-..-49}{89}$ thực hiện phép tính