This month BUMN offered IPOs to $4$ of its companies on the capital market. The probability of a price increase in share A $=0\mathrm{.}60,$ share B $=0\mathrm{.}80,$ share C $=0\mathrm{.}40$ and share D $=0\mathrm{.}55.$ The probability of a price decrease in share A $=0\mathrm{.}15,$ share B $=0\mathrm{.}05,$ share C $=0\mathrm{.}25$ and share D $=0\mathrm{.}10,$ while the other is the probability that the price of these shares remains the same.

Calculate the probability:

a$.$ Two of these shares will experience an increase in price.

b$.$ At most $2$ shares have a fixed price.

c$.$ At least $2$ of these shares will experience a decline or have a fixed price.