A shop owner sold 175 shirts. He donated 1/9 of the remaining shirts to charity and had 4/7 of the shirts left. How many shirts did he have at first?

I think the answer is 490 shirts, right?

because

firstly, let X be the total shirts you need to find

then we have 175/X is the rate of shirts which the shop owner sold in the begining

so the remaining rate is (1-175/X)

the shop owner sold again and the second rate which shows the shirts was donated to the charity is (1-175/X) x1/9

so the overall rate that shows the owner shop sold in 2 turns is 175/X + (1-175/X) x1/9

that rate below is also 1-4/7 or 3/7

so solves 175/X + (1-175/X) x1/9=3/7X=490