Solve each sentence in your head.

1.    n + 4 = 20                                    n = ______
 

2.    a - 6 = 20                                    a = ______
 

3.    n + n + n + n = 20                        n = ______
 

4.    4 × n + 3 = 19                              n  = ______
 

5.    b + 3 + 5 = 23                              b = ______
 

6.    y + y + y = 33                                y = ______
 

7.    a² + a = 42                                    a = ______
 

8.    2 × n - 13 = 37                              n = ______
 

9.    h + 17 = 33                                    h = ______
 

10.    (a - 10) + 4 = 20                          a = ______
 

11.    34 - n = 22                                   n = ______
 

12.    18 - h = 12                                   h = ______
 

13.    30 - ( 14 - a) = 22                        a = ______
 

14.    2 × n + n = 24                               n = ______