Verified answer

0,6 * x + 3.4 *x+0.9*x= 7.35

(0.6+3.4+0.9) * x = 7.35

4.9 *x =7.35

x= 7.35 : 4.9

x= 1.5

19*x+24*x-13*x=870

(19+24-13)*x = 870

30*x= 870

x= 870:30

x= 29

6.7*x + 2.5*x=69

(6.7+2.5) *x =69

9.2 * x = 69

x= 69 : 9.2

x= 7.5