Question

In a 3-digit number, the hundreds digit is four more than the units digit, and the tens digit is three less than the sum of the other two digits. If the sum of all three digits in the number is 17, find the free digits. Then find the number

Answer 1

Explanation:

the number is abc

c = units digit

b = tens digit

a = hundreds digit

a = c + 4

b = (a + c) - 3

a + b + c = 17

we use the first equation in the second and get

b = (c + 4 + c) - 3 = 2c + 4 - 3 = 2c + 1

abd we use the first and the second equation more in the third and get

c + 4 + 2c + 1 + c = 17

4c = 12

c = 3

b = 2c + 1 = 2×3 + 1 = 6 + 1 = 7

a = c + 4 = 3 + 4 = 7

so, the number is

773