Question

Ana se pregateste pentru crosul tineretului in trei etape, alergand, in total 152 km. In primele doua etape la un loc alearga cu 8 km mai mult decat in a treia. In etapa a doua alearga cu 10 km mai putin decat dublul distantei alergate in prima.
a) Cati kilometri a alergat Ana in primele doua etape la un loc?
b) Cati kilometri a alergat Ana in fiecare etapa de pregatire?

Answer 1

I=prima etapa
II= a doua etapa
III= a treia etapa
I+II+III=152 km
I+II=III+8km
II=2 ori I-10km
a)III+III+8km=152km
2 ori III=152km-8km=144km
2 ori III=144km
III=144km:2=72km
daca I+II=III+8km
I+II=72km+8km
I+II=80km
b)I+II=80km
II=2 ori I-10km
I+2I-10km=80km
I+2I=80km+10km=90km
3I=90km
I=90km:3=30km
I=30km
II=30 km x 2-10km
II=50km
Deci I=30km
II=50km
III=72km