Question

what is the distance between the line y + 3=0 and 2y-5=0

Answer 1

first line is
$2y - 5 = 0 \\ y = 5 \div 2 \\ let \: \: a \: point \: on \: this \: line(0..5 \div 2)$
second line is
y=-3
any point on it (0,-3)
so distance
$d = (5 \div 2) - ( - 3) = 11 \div 2$