Can somebody help? Do not answer if you don't know.

10.8amu

Explanation:

Given parameters:

Abundance of B - 10  = 20% = 0.2

Abundance of B - 11  = 80% = 0.8

Unknown:

Atomic mass of Boron = ?

Solution:

The atomic mass of Boron can be can be calculated using the expression below;

 Atomic mass  = (abundance of B - 10 x mass of isotope B - 10 ) +( abundance of  B - 11 x mass of isotope B- 11)

 Atomic mass  = (0.2 x 10) + (0.8 x 11) = 2 + 8.8  = 10.8amu

answer: your mm

explanation: