B2. Sašo prepared for a cycling marathon for seven weeks. He cycled three times a week. Each subsequent week, he cycled $30 \mathrm{~km}$ more than the previous week. Each week, the first two days he cycled the same distance, and on the third day, he cycled $10 \mathrm{~km}$ more than the first two days. In the first week, he cycled $70 \mathrm{~km}$.

A. How many km did Sašo cycle on the first day of preparation?

B. How many $\mathrm{km}$ did he cycle on the last day of preparation?

C. How many km did he cycle in the seven-week preparation?
B2. The equation $x+x+(x+10)=70$ describes the kilometers driven in the first week. On the first day of preparation, he drove $x=20 \mathrm{~km}$. For the last week of preparation, we write the equation $z+z+(z+10)=250, z=80$. On the last day of preparation, Sašo drove $z+10=90 \mathrm{~km}$. Since each week he drives $30 \mathrm{~km}$ more than the previous week, the total number of kilometers driven is: $70+100+130+160+190+220+250=1120$ $\mathrm{km}$.

A. On the first day, he drove $20 \mathrm{~km}$. $1 \mathrm{t}$

B. In the seventh week, he cycled $250 \mathrm{~km}$. . .

$2 \mathrm{t}$

C. In seven weeks, he cycled $1120 \mathrm{~km}$.