Emma bought some kilograms of rice. She ate 12 kg of rice per month for 3 months. After 3 months, she had 15 kg rice left. How much rice had Emma bought?
total rice consumed = 36
x - 36 = 15
Solving for x,
x - 36 + 36 = 15+36
x = 51kg
So the amount of rice Emma bought initially was 51 kg.