**There were some black and white marbles in a bag. If 20 black marbles are removed from the bag, the total number of marbles will be 7 times the number of black marbles left. If 50 white marbles are removed from the bag, the total number of marbles left will be 5 times the number of black marbles left. How many marbles are there in the bag?**

**Solution**

20 black marbles (removed)

Black --> 1 unit + (20)

White --> 6 units

50 white marbles (removed)

Black --> 1 part

White --> 4 parts + (50)

(Black) 1 unit + 20 --> 1 part ...... (x4)*

(White) 6 units --> 4 parts + 50

(Black) 4 units + 80 --> 4 parts

(White) 6 units --> 4 parts + 50

*(x4) to make an equal number of 4 parts for both Black and White Marbles

(White Marbles) - (Black Marbles)

6 units - 4 units - 80 --> 4 parts + 50 - 4 parts

2 units - 80 --> 50

2 units --> 50 + 80

2 units --> 130

1 unit --> 130 divided by 2 = 65

Total number of marbles

Black --> 1 unit + 20

White --> 6 units

--> 7 units + 20

= (7 x 65) + 20

= 475

Answer: 475 marbles

Answer: 475 marbles

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