The sum of a 2 digit # is 15. If the digits are reversed the # is 27 less than the first #Find the first #?

Answer 1

If the number is of the form ab it can be written 10a + b
The reverse can be written 10b + a

so

10b + a + 27 = 10a + b
9b + 27 = a
b + 3 = a

The two digits equal 15, so a + b = 15
a = 15 - b

Using substitution

b + 3 = 15 - b
2b = 12
b = 6

a = 6 + 3 = 9

The number is 96

Answer 2

Let A and B be the two digits of the number "AB". Notice that you can write the actual value of this number as 10A + B (for example, 75 = 70+ 5, or 7*10 + 5). If the sum of the digits is 15, then A+B = 15.

If you reversed the digits of the number, then that number would be 10B + A. If this is 27 less than the original number, then:

(10B + A) = (10A + B) - 27

Combine this with A+B=15, and you have two equations with two unknowns. Solve this for A and B, and you have the two digits of the original number:

(10B + A) = (10A + B) - 27
9B - 9A = -27
B - A = -3
A - B = 3

Add this to A+B=15, and you get 2A=18, so A=9. This means B=15-9=6, so the original number is 96.

Answer 3

Let the digits be a and b (in that order).
Then a + b = 15.
The first number is 10a + b and the second is 10b + a, so we have
10b + a = (10a + b) - 27
=> 9b = 9a - 27
=> b = a - 3
So a + (a - 3) = 15
=> 2a = 18
=> a = 9, b = 6.
So the number is 96.

Answer 4

96 is the first number

heres the reasoning:

9 + 6 = 15
96 - 69 = 27

Answer 5

96

Answer 6

9 because there are only two sets of numbers that add up to 15, 8&7, 9&6. the difference between 96 and 69 is twenty seven

Answer 7

96 ==> 69

Answer 8

96

Answer 9

let the digits be a and b.

10a + b = 15
10b + a = 10a + b -27

... now find the values of a and b that satisfy both equations
(this is called a system of linear equations).