y can be rounded up to 1.51 from a minimum value of 1.505
This is the lower bound.
y can be rounded down to 1.51 from a maximum value of 1.515
this is the upper bound.
y is between the lower bound and the upper bound so y is between 1.505 and 1.515
This is shown as 1.595<=y<1.515
<= is the typed out version of (greater than/equal to) which is < with a line under it.