13+28х=5х+17+23х
28х-5х-23х=17-13
х=4
5-3х+4=17х+9-20х
-3х-17х+20х=9-5-4
х=0
1) 120=2*2*3*2*5
140=2*7*2*5
НОД (120,140)= 2*2*5=20
НОК (140,120)=2*7*2*5*3*2=840
2. 300:1,2,3,5,6,10,15,20,30,50,60,100,150,300 (14 делителей)
450:1,2,3,5,6,9,10,15,18,25,30,45,50,75,90,150,225,450 (18 делителей)
28.3+1.8+6-18.2+11.7=28,3+11,7+6+1,8-18,2=47,8-18,2=29,6