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 check the student’s answer?

Antonio has blue marbles

Step-by-step explanation:

Let

x------> the number of green marbles

y------> the number of red marbles

z------> the number of blue marbles

we know that

-----> equation A

----> equation B

----> equation C

Substitute equation B and equation C in equation A and solve for z

Subtract both sides

answer: 2x + 2 − 2 = 10 − 2; subtraction property of equality

step-by-step explanation: