Question

    7Х-12
 5+   ---------  =Х+13
       3
7У-1        У+1      2У+5
-------  -  -----  =   ---------
12            4            3

Answer 1

1)5+(7х-12)/3=х+13

(3+7х)/3=х+13 

(3+7х-3х-39)/3=0

(4х-36)/3=0

х=9

2)(7у-1-3*(у+1)-4*(2у+5))/12=0

(7у-1-3у-3-8у-20)/12=0

(-4у-24)/12=0

 -4у-24=0

у=-6