Which of the following inequality represents the consumer's budget constraint?

$p_1 x_1+p_2 x_2 \leq M$

$p_1 x_1+p_2 x_2 \leq M$

Suppose the income of the consumer is M and the prices of bananas and mangoes are p1 and p2 respectively . If the consumer wants to buy x1 quantities of bananas, she will have to spend p1 x1 amount of money. Similarly, if the consumer wants to buy x2 quantities of mangoes, she will have to spend p2 x2 amount of money. Therefore, if the consumer wants to buy the bundle consisting of x1 quantities of bananas and x2 quantities of mangoes, she will have to spend p1 x1 + p2 x2 amount of money. She can buy this bundle only if she has at least $p_1 x_1+p_2 x_2$ amount of money. Given the prices of the goods and the income of a consumer, she can choose any bundle as long as it costs less than or equal to the income she has. In other words, the consumer can buy any bundle (x1 , x2 ) such that

 $p_1 x_1+p_2 x_2 \leq M$ (2.1)

The inequality (2.1) is called the consumer’s budget constraint. The set of bundles available to the consumer is called the budget set. The budget set is thus the collection of all bundles that the consumer can buy with her income at the prevailing market prices.