Question 1 The sum of three numbers is 81. The third number is 4 times the first. The first number is 9 more than the second. What are the numbers?

Answer 1

X1 + X2 + X3 = 81.

Given that X3 = 4X1 and X1 = X2 + 9. Since X1 = X2 + 9, X2 = X1 - 9.

Rewrite the original equation in terms of X1:

X1 + (X1 - 9) + 4X1 = 81 ==> 6X1 - 9 = 81 ==> 6X1 = 90. Divide both sides by 6 to get X1 = 15.

X2 = X1 - 9 ==> X2 = 15 - 9 = 6.

X3 = 4X1 = 4*15 = 60.

15 + 6 + 60 = 81.

Answer 2

x + x-9+ 4x = 81

6x - 9 = 81

6x = 90

x = 90/6 = 15

15, 6 and 60