Let's work out a math problem for me with a formula A is 5 / 21 of B and C is 4 / 5 of A. A, B and C donate 310 to each of them. How much do they donate? Write down the formula

Let's work out a math problem for me with a formula A is 5 / 21 of B and C is 4 / 5 of A. A, B and C donate 310 to each of them. How much do they donate? Write down the formula

It's a process, right
Let B be X
5/21x+4/21x+x=310
10/7x=310
x=217
B is 217 yuan
A 155 / 3 yuan
C 124 / 3 yuan