Question

The sum of three numbers is 15, the second number is 2 times the first and the third number is 20 less than the second. What is the third number?

Answer 1

Answer:

-6

Step-by-step explanation:

Let no. be x, y, z

According to given information,

y = 2x

z = y - 20 = 2x - 20

x + y + z = 15

=> x + 2x + 2x - 20 = 15

=> x = 7, y = 14, z = - 6

Answer 2

Answer:

let the first number be X;

then, the second number is two times of first , this means that (2*X) '

and the third is 20 less than second ,means that     {(2*X) - (20)}  ;

now ; according to questions;

X + 2*X + ( 2*X - 20 ) = 15

5X - 20 =  15

5X = 15 + 20      (subtract changed into addition)

5X= 35

X= 35/5             (multiply changed into divid)

X= 7

and  first number is 7

second number is 14

third number is -6