When ever I encounter problem like this, I make the equation become:
z = anything buy z.
First, you want to get 2/5 to the other side, to do so, you need to multiply 5/2 on both side. then you are left with z+1=5/2 y. Then you subtract 1 from both sides to make z on its own. The answer should be z = 3/2y or z= 1
y
2/5(z+1)=y
2/5(z+1)5/2=5/2y
z+1=5/2y
z+1-1=5/2y-1
z=3/2y or z=
1
y