first you need to know that if a/b = c/d then a*d = c*b
so, (x-500000)*(500000) = (60x)*(3000000)
500000x-250000000000=180000000x
now put anything with x on side
500000x-180000000x =250000000000
add the terms on left, you will have ax=b
divide b by a to get x --> x= b/a