Answer:
Step 2
Step-by-step explanation:
Michelle's step in trying to solve the equation is given below:

Michelle made a mistake in Step 2.
The right hand side of Step 1: 
Rather, the correct sum is:

Answer:
1:6
2:2
3:4, it's twice the MAD.
Step-by-step explanation:
6-2=4
MAD: 2
Divide both sides by 8.5 to get b on its own
68/8.5 = 8
So b = 8
Answer:
63
Step-by-step explanation:
We are taking a dilation of 3, so that means we are multiplying by 3. We multiply 3 to 21 to get 63.