1. Evaluate a + b if a = 7 and b = 3.

a + b =

2. Evaluate a - b if a = 8 and b = 2.

a - b =

3. Evaluate ab if a = 3 and b = -5.

ab =

4. Evaluate 2a + b if a = 4 and b = -8.

2a + b =

5. Evaluate abc if a = 4, b = 5 and c = 2.

abc =

6. Evaluate 4yz - 5 if y = 2 and z = 10.

4yz - 5 =

7. Evaluate y - z if y = -2 and z = -6.

y - z =

8. Evaluate -a - b - ab if a = -3 and b = -4.

-a - b - ab=

9. Evaluate -x - (-a + b)
    if x = 2, a = -4 and b = -6.

-x - (-a + b) =

10. Evaluate mx + b if m = -2, x = 4 and b = -3.

mx + b =

11. Evaluate -(m + x)(-a + mx)
      if m = 2, x = -3 and a = -4.

-(m + x)(-a + mx) =

12. Evaluate -xa(x - a) + a
      if x = 4 and a = -2.

-xa(x - a) + a =

13. Evaluate x - xy if x = -2 and y = 3.

x - xy =

14. Evaluate a - (ab - a) if a = -4 and b = -2.

a - (ab - a) =

15. Evaluate x - ab(a - b)
      if x = -3, a = -2 and b = -4.

x - ab(a - b) =

16. Evaluate -xa(a + x) + x
      if x = -4 and a = -2.

-xa(a + x) + x =

17. Evaluate xm - 2m if x = -2 and m = -3.

xm - 2m =

18. Evaluate 2abc - 3ab
      if a = 2, b = -3 and c = 4.

2abc - 3ab  =

19. Evaluate a² - b if a = 4 and b = -8.

a² - b =

20. Evaluate a² + b² if a = -3 and b = -7.

a² + b² =