1.
3.8x+4.94-9.5=0
3.8x-4.56=0
x=4.56/3.8
x=456/380
x=1.2
2.
26.1-5.8x-8.7=0
17.4-5.8x=0
-5.8x=-17.4
5.8x=17.4
x=3
Решаем с помощью пропорции
2,5 см ------- 425 км
3,7 см -------- х км
х = 3,7 * 425 : 2,5 = 629 км
1) 13/17+5/16+4/17+7/16=13/17+4/17+5/16+7/16=(13+
4)/17+(5+7)/16=17/17+12/16=1+3/4=7/4
2) 5/8+19/36+(-1/36)=5/8+(19-1)/36=5/8+18/36=5/8+1/2=(5+4)/8=9/8
3) 14/39-(1/12+1/39)=14/39-1/39-1/12=(14-1)/39-1/12=13/39-1/12=1/3-1/12=(4-1)/12=3/12=1/4