Could i get some with these three questions (17, 19, 21)

Simply substitute the given number for all the equations.

17) 5b + 1 = 16 where b is -3

5(-3) + 1 = 16

-15 + 1 = 16

-14 ≠ 16

So, the given number is not a solution.

19) 2 = 10 - 4y where y is 2

2 = 10 - 4(2)

2 = 10 - 8

2 = 2

The given number is a solution.

21) -6b + 5 = 1 where b is 0.5

-6(0.5) + 5 = 1

-3 + 5 = 1

2 ≠ 1

The given number is not a solution.

The correct answers are -14 ≠ 16, 2 = 2 and then 2 ≠ 1 
Good Luck!! :)