We will define the following variables to solve the problem:
 x = amount of round trips from 10 tons truck
 y = amount of round trips from 12 tons truck
 We write the system of equations:
 x + y = 20
 10x + 12y = 226
 The solution to the system of equations is:
 x = 7
 y = 13
 Answer:
 10 tons truck makes 7 round trips
 12 tons truck makes 13 round trips
