1.
18x+6y/7xy - 4x-15y/7xy=
18х+6у-4х+15у / 7ху=
14х+21у/ 7ху=
7(2х+3у) / 7ху=
2х+3у /ху

2.
14p^4/11p^3 * 22p^2/63p^2=
2p^4/ p^3 * 2p^2/9p^2=
4p^4+2 /9p^3+2=
4/9* р^6-5= 4/9 р

3.
5x²+7(x-2)=4x²-14
5x²+7x-14-4x²+14=0
х²+7х=0
х(х+7)=0
х1=0
х+7=0
х2=-7

4.
5x+8 ≤ 4x-12
5x-4х ≤ -12-8
х ≤ -20