If {X: 2 d- x d- 19; X integer} and 7 + x = 4 (mod 9), find the highest value of x

The sum 11011\(_2\), 11111\(_2\) and 10m10n0\(_2\). Find the value of m and n.

A trader bought an engine for $15,000.00 outside Nigeria. If the exchange rate is $0.075 to N1.00, how much did the engine cost in Naira?

Find the 7th term of the sequence: 2, 5, 10, 17, 26,...