Answer:
40
Explanation:
Just look up the conversion factor and set up the proportion.
1 dm = 1/10 th of a meter
x dm = 4 meters. Cross multiply.
1 dm * 4m = x * 1/10 of a meter. Change 1/10 to a decimal.
1 dm * 4 m = x * 0.1 m Divide by 0.1
1 dm * 4 m /0.1 m = x
x = 40 dm