Two numbers are such that the first is half as large as the other. If the sum of the two numbers is 720, what are the numbers?

Asked on by thomas666

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justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

Let the number we need to find be x and y.

The sum of the numbers is x + y = 720...(1)

We also know that one number is half the other. x = y/2

substitute y = 2x in equation (1)

x + y = 720

=> x + 2x = 720

=> 3x = 720

=> x = 720/3

=> x = 240

y = 2*x = 480

This gives the two numbers as 240 and 480.

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hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted on

Let the first number be x and the second number be y.

Given that x is half y

==> x = y/2 .............(1)

Also, given that the sum of the numbers is 720.

==> x + y = 720.............(2)

Now we will substitute (1) into (2).

==> (y/2) + y = 720

We will multiply by 2.

==> y+ 2y = 1440

==> 3y = 1440

Now we will divide by 3.

==> y= 1440/3 = 480

==> y= 480

==> x= 480/2 = 240

Then the numbers are 480 and 240.

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