Respuesta :

altavistard
You want y?  One way to get y alone would be to mult. all 3 terms by (7/5):

(7/5)(5/7)y = (7/5)*3 - (7/5)(-1/5).  This simplifies to:

              y = 21/5 * 7/25, or y = 147 / 125.

You could check this using decimal fractions:

                y = 4.20 * 0.28 = 1.176 = 147 / 125.