Answer:
8.
Denote the equation : y = ax + b
Use the first 2 values of x and y in table:
3a + b = 21
5a + b = 35
Subtract the 2 equations:
=> 2a = 14 => a = 7 => b = 21 - 3 x 7 = 0
=> The solution is y = 7x
9.
Denote the equation : y = ax + b
Use the first 2 values of x and y in table:
5a + b = 17
10a + b = 22
Subtract the 2 equations:
=> 5a = 5 => a = 1 => b = 17 - 5 x 1 = 17 - 5 = 12
=> The solution is y = x + 12
Hope this helps!
:)