Answer:
23
Explanation:
Compatible numbers : numbers that are easy to add, subtract, multiply, or divide mentally. They are close in value to the actual numbers, although they do not necessary need to be rounded numbers.
-138 is close to -137.56
-6 is close to -6.12
![\implies (-138)/(-6)](https://img.qammunity.org/2023/formulas/mathematics/college/ezosdr84kxk6lek992bjejowy0s2u74rxi.png)
Divide the top and bottom by -2:
![\implies (69)/(3)](https://img.qammunity.org/2023/formulas/mathematics/college/aq8dcgmtek0z6u205dyhumhxyjscm4ufyj.png)
Divide the top and bottom by 3
![\implies 23](https://img.qammunity.org/2023/formulas/mathematics/college/kc3fhd49uol5qog5yv1stkk5kf9akftjnj.png)
If this is too difficult to divide mentally, you could use -140 and -7:
![\implies (-140)/(-7)](https://img.qammunity.org/2023/formulas/mathematics/college/u6gmygc9wc0wmd2pr9irw5a6w35hx71oxm.png)
As 2 x 7 = 14, then 20 x 7 = 140, so the answer is 20.