The second number is thrice the third number. The first number is one less than the second number. Find the 3 numbers whose sum is 48.

Your problem contains three sentences. Each one of those sentences spells out an equation. For example, if our three numbers are a, b, and c, then the first sentence says b = 3c. Can you come up with the other two equations?

Once you have the three equations, it's simply a matter of solving them simultaneously. If you don't know how to do that, let us know. We can guide you.

1st number is 20
2nd number is 21
3rd number is 7

let
third number=x
second number=3x
first number=3x-1
(3x-1)+3x+x=48
7x-1=48
7x=48+1
7x=49
x=7:third number
3x=21:second number
3x-1=20:first number

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A park in the shape of a rectangle has dimensions 60 m by 100 m.If the park contains a rectangular garden enclosed by a concrete terrace, how wide is the terrace if the area of the garden is one-half of the area of the park?