Question

The sum of two numbers is 120 and one of the numbers is 3 times the other.

Find the equation

Answer 1

let the first no. be x
then second is 3x
so
this is the equation
x + 3x = 120
=>4x = 120
=>x = 120/4
=>x = 30
so second no. =3 × 30 = 90

hope it help you

Answer 2

Here is complete solution❤❤

Let the number be A and B
A + B = 120
A = 3B
Substitute the value of A from the second equation into the first.
(3B) + B = 120
4B = 120
Divide each side by 4
B = 30 
so A = 90