the ratio of red and green marbles in a box are 3;7 how many marbles are in the box if there are 20 fewer red marbles than blue?

50 marbles
Step-by-step explanation:
The difference between the ratio of the red and green marbles is 4 units and the number value is 20 so its safe to say that 4 units is equal to 20 and thus one unit is 5 and because of the fact that there is a total of 10 units of marbles in the box according to the ratio, just multiply 5 and 10 which you get 50.
4 units = 20
1 unit = 20÷4 = 5
Total = 10 units
10 unit = 5 ×10 = 50
Ans : 50 marbles

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