1. Adamu spends 3/5 of his monthly allowance on food and 1/4 on learning materials. If the amount he spends on food and learning materials is N330 less than his allowance, how much is his monthly allowance?
Let Adamu's monthly allowance be represented by A.
From the given information, he spends 3/5 of his monthly allowance on food and 1/4 on learning materials.
Therefore, he spends (3/5)A on food and (1/4)A on learning materials.
The amount he spends on food and learning materials is N330 less than his allowance, so we can write the equation (3/5)A + (1/4)A = A - N330.
Multiplying through by 20 to eliminate the fractions, we get 12A + 5A = 20A - 6600.
Simplifying, we have 17A = 20A - 6600.
Combining like terms, we have 3A = 6600.
Dividing both sides by 3, we get A = 6600/3 = N2200.
Therefore, Adamu's monthly allowance is N2200. Answer: \boxed{2200}.