Question

a number is fourth- fifths of the other. if their sum is 180 . find the number​

Answer 1

Step-by-step explanation:

Given :-

A number is fourth- fifths of the other.Their sum is 180 .

To find:-

Find the number ?

Solution:-

Let the other number be X

Then the number = 4/5th of the other

=> (4/5) of X

=> (4/5)×X

=>(4×X)/5

=> 4X/5

The number = 4X/5

Their sum

=> (4X/5)+X

=> (4X+5X)/5

=> 9X/5

Their sum = 9X/5

According to the given problem.

Their sum = 180

=> 9X/5 = 180

=> 9X = 180×5

=> 9X = 900

=>X = 900/9

=> X = 100

The other number = 100

The number = (4/5)th of the number

=> (4/5)×100

=> (4×100)/5

=> 400/5

=>80

Answer:-

The required number for the given problem is 80

Check:-

The number = 80

The other number = 100

Their sum = 80+100=180

Verified the given relations in the given problem.

Answer 2

Step-by-step explanation:

let the number be x

let the other number be 4/5 of x = 4x/5

so the equation is

x+4x/5=180

(5x+4x)/5=180

9x/5=180

9x=180×5

9x=900

x=900/9=100

Verification:

100+4/5×100=180

100+80=180