1.b^{13+1+21+20} = b^{55}
2.( 4^{2} )^{4} * (2^{2})^{10} * (8^{2})^{5} = 4^{16} * 2^{10} * 8^{10} = (2^{2} )^{16} * 2^{10} * (2^{3} )^{10} = 2^{32} * 2^{10}* 2^{30}= 2^{32+10+30}= 2^{72}
3. c^{58-39-9}= c^{28}
4. (5^{3} )^{42} : (5^{2} )63= 5^{126}: 5^{126}= 5^{126-126} = 5^{0} =1