Originally Posted by

**sigma1** hello

three groups of children A B and C sold sweets on three consecutive days of the week. On day 1 the three groups made a profit of $20, with group A B, and C making an average profit per child of 1$ 2$ and 1$ respectively. on day 2 the three respective groups made a profit per child of 3$ -1$ and 2$ respectively. on the whole day they made a profit of 22 on that day. on day 3 the total profit was only 7$ and profits per child were 2$ 1$ and -4$ for the respective groups.

i have come up with the following equations. are they correct?

A1+B2+C= 20

A3-B+2C=22

A3+B-4C=7

am suposed to solve for the number of students in each group by expressing in echelon form then row reduce to solve.. i would like to see how its done.