Answer:
increase his consumption of product Y and decrease his consumption of product X
Explanation:
Base on the scenario been described in the question, Oscar make purchase of a X product which he already has, which after consuming has a 10 utils costing him $5, he also purchase another product Y he which after consuming has 8 until costing, this suggest that Oscar reduce his consumption on X and increase his consumption on Y according to the equal marginal principle.
The equal marginal principle talks about the behavior of a consumer in sharing his available income within various goods and services. This law states that how a consumer distributes his money income within various goods to be able obtain maximum satisfaction.