They are parallel when the slopes are the same
example:
y=2x+3
y=2x-5
First change the fraction to decimals or common denominators.
3/4 = 0.75 and 1/5 = 0.2
0.75 + 0.2 = 0.95 = 95/100 = 19/20
(3/4) = (15/20)
(1/5) = (4/20)
(15/20) + (4/20) = 19/20
To make pastry for an apple pie, you need 4 oz flour and 2 oz fat. The ratio of flour to fat is
4 : 2 .
But this ratio can be simplified in the same way that two fractions can be simplified. We just
cancel by a common factor. So
4 : 2 = 2 : 1 .
