Answer:
30 mm
Step-by-step explanation:
To find out how many mm he grew in a year, multiply 18 by 10
18*10=180
So he grew 180 mm in 1 year
To find per month, divide by 12 (12 months in a year)
180/12=15
So, he grew 15 mm per month
To find two months, multiply 15 by 2
15*2=30
In 2 months, he grew 30 mm
Hope this helps! :)
