Answer:
30 was incorrectly factored
Step-by-step explanation:
From your lists, you can see that common factors of 18 and 30 include ...
2, 3, 6
So any of these can be factored out of the expression.
18 = 2·9; 30 = 2·15 ⇒ = 2(9 +15)
18 = 3·6; 30 = 3·10 ⇒ = 3(6 +10)
18 = 6·3; 30 = 6·5 ⇒ = 6(3 +5)
The error is that the work was not checked. Factoring of 18 is correct, but the factoring of 30 is not correct.
The error can be corrected by using an appropriate factoring.
swapping "3" and "6": 18 + 30 = 3(6 +10)
properly factoring 6 from 30: 18 +30 = 6(3 +5)
