Question

(1 2/7 y - 1/2):2,5=5,2

Answer 1

12/7y-1/2=5,1*2,5
12/7y-1/2=13
12/7y=13-0,5
12/7y=12,5
12=12,5*7y
6y=0,96
y=0,96/7
y=0,137...
вроде так