Find the value of x.

[4/5](15x-25)-1= [3/7] (21-7x)        distribute the 4/5 and 3/7 over the terms in parentheses

12x - 20  - 1   =  9 - 3x       combine like terms

12x - 21  = 9 - 3x               add 3x, 21 to both sides

15x  = 30      divide both sides by 15

x  = 2