Respuesta :

RASEA23
It erodes 1/3 every 3 months. There are 4- 3 months in a year. 
1/3 x 4= 4/3 ft
4/3 ft a year
SmarticalParticals
In the comments you said you meant every 3 months so... There are 4, 3 month periods in a year so 4 × 1/3 = 4/3 = 1 1/3 feet per year.