15a/5-a + 12n/(3-n)² * 15-5n/4=
12n/(3-n)² * 15-5n/4=12n/(3-n)(3-n)*5(3-n)/4=15n/3-n
15a/5-a+15n/3-n=(15a(3-n)+15n(5-a))/(5-a)(3-n)=(45a-30an+75n)/15-5n-2an=
=5(9a-6an+15n)/5(3-n-0,4an)=
=9a-6an+15n/3-n-0,4an
15a/5-a + 12n/(3-n)² * 15-5n/4=
12n/(3-n)² * 15-5n/4=12n/(3-n)(3-n)*5(3-n)/4=15n/3-n
15a/5-a+15n/3-n=(15a(3-n)+15n(5-a))/(5-a)(3-n)=(45a-30an+75n)/15-5n-2an=
=5(9a-6an+15n)/5(3-n-0,4an)=
=9a-6an+15n/3-n-0,4an