Question

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

Answer 1

Answer:

a = 7, b = 14, c = -6

Step-by-step explanation:

1. let a+ b+ c = 15

( According to question) b = 2a ----- 2.

c = 2a - 20 -----3.

put the value of b and c in equation 1.

a + 2a + 2a - 20 = 15

5a - 20 = 15

5a = 15 + 20

5a = 35

a = 7

put the value of a in equation 2.

b = 2a = 2(7) = 14

put the value of a in equation 3.

c = 2a - 20

= 2(7) - 20

= 14 - 20 = -6