Answer:
Step-by-step explanation:
1) 10a - 7a = 3a {10a & 7a are like terms. So we can subtract}
5a + 2a - 4a = 7a - 4a = 3a {5a, 2a, 4a are like tems}
So, 10a - 7a and 5a + 2a - 4a are equivalent expressions
2) 9 - 4y and 4y - 9 are not equivalent
3) 6 + s means 6 is added to s
6s means 6 is multiplied by s.
6 + s and 6s are not equivalent expressions
4) 2c + 6c +9 - c - 4 = 2c + 6c - c + 9 - 4
= 8c - c + 5
= 7c + 5
7c + 5
2c + 6c +9 - c - 4 and 7c + 5 are equivalent expressions
