Question

Antonio has a total of 55 marbles. He has 15 green marbles and 12 red marbles. The rest of the marbles are

blue. How many blue marbles does he have
A student solves this problem by writing an equation. Which strategy could help check the student's answer?
final answer

Answer 1

15

+12

=27

55

-27

=28

28 of the marbles are blue

Answer 2

Add 12 and 15 to their X value.

Explanation:

X = 28, but they could check by adding 12 and 15 to see if it adds to 55.