Let total earnings = x
Target question: how much does he save every month?
Statement 1: Gandalf spends 1/4th of his earnings on rent, 1/2 of his earnings he saves, and the remaining amount he spends on food.
$$rent=\frac{1x}{4};\ savings\ =\ \frac{1x}{2}$$
$$Amount\ spent\ on\ food=x-\frac{x}{4}-\frac{x}{2}$$
$$Amount\ spent\ on\ food=\left(\frac{4-1-2}{4}\right)x$$
$$=\frac{x}{4}$$
From question stem; Gandalf spends $1400 on food.
Therefore, x/4 = 1400
x = 5600 and
Savings = 1/2 * 5600 = $2800
From the remaining 4200, the total amount of money he saves cannot be evaluated with the information provided in this statement. Hence, statement 2 is NOT SUFFICIENT.
Since only statement 1 is SUFFICIENT, Option A is the correct answer.