<image>In addition to the weight of the basket a single balloon can lift $80 \mathrm{~kg}$. 2 balloons can lift $180 \mathrm{~kg}$ in addition to the weight of the basket. How heavy is the basket?
A. $60 \mathrm{~kg}$
B. $50 \mathrm{~kg}$
C. $40 \mathrm{~kg}$
D. $30 \mathrm{~kg}$
E. $20 \mathrm{~kg}$