Yes they are equivalent because their ratio is 9
81/9= 9
63/7=9
-30, 10*4=40 so you do 9-40+1 which is equal to -30
Use distributive property: multiply the number outside the bracket by each number inside it
1. 14x+21=35 14x=14 x=1
2. -32x-24=40 -32x=64 x= -2
3. 16-10x=-44 -10x=-60 x=6
Here’s an explanation! let me know if you need further clarification