The sum of three numbers is 81. The third number is 3 times the first. The first number is 9 more than the second. What are the numbers?

Answer 1

Here's what we know:

a + b + c = 81 (three numbers add up to 81)

c = 3a (the third number is 3 times first)

a = b + 9 (the first is 9 more than second)

Now that we have values for our variables, let's plug them in:

b + 9 + b + 3a = 81

b + 9 + b + 3(b + 9) = 81

b + 9 + b + 3b + 27 = 81

Simplify:

5b + 36 = 81

Subtract 36 from both sides:

5b = 45

Divide by 5:

b = 9

Now that we know b, we can find a:

a = 9 + 9

a = 18

And from here, c:

c = 3 * 19

c = 54

check:

18 + 9 + 54 = 81

81 = 81