Answer:
substitution
Step-by-step explanation:
All the choices are correct.
_____
In our base-10 number system, moving a digit one place to the left multiplies its value by 10. Moving it one place to the right multiplies its value by 1/10.
You know already that 1,000 has 10 times the value of 100, and 1/10 the value of 10,000.
Since tenths are 10 hundredths in each, 4 tenths equal to 40 hundredths.
The equasion has only one solution.
