Estimate the difference of 10 2/3 - 6 9/11

What is the simplified form of 7 √x • 7 √x • 7 √x • 7 √x?

Successful implementation of a new system is based on three independent modules. module 1 works properly with probability 0.96. for modules 2 and 3, these probabilities equal 0.95 and 0.90. compute the probability that at least one of these three modules fails to work properly.

What is the missing step in this proof ?