Răspuns:
a=7/20 x t a= prima zi, b = a doua zi, c=a treia zi ,t = total
b= 2/5 x r c=624 km
624= 3/5 x r => R =624 x 5: 3= 3120 :3= 1040
r =1040 km b= 2x 1040 : 5= 2080 :5= 416 km ( a doua zi)
r= 13/20 x t => t= 20 x r :13= 20 x 1040 :13= 1600 km
t= 1600 km total a= 7 * 1600:20= 560 km
t= 560 + 416 + 624= 1600 km