The sum of the digits of a 2 digit number is 10. The value of the number is four more than 15 times

Discussion in 'Calculator Requests' started by math_celebrity, Aug 1, 2019.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    The sum of the digits of a 2 digit number is 10. The value of the number is four more than 15 times the unit digit. Find the number.

    Let the digits be (x)(y) where t is the tens digit, and o is the ones digit. We're given:
    1. x + y = 10
    2. 10x+ y = 15y + 4
    Simplifying Equation (2) by subtracting y from each side, we get:
    10x = 14y + 4

    Rearranging equation (1), we get:
    x = 10 - y

    Substitute this into simplified equation (2):
    10(10 - y) = 14y + 4
    100 - 10y = 14y + 4

    Typing this equation into our search engine, we get:
    y = 4

    Plug this into rearranged equation (1), we get:
    x = 10 - 4
    x = 6

    So our number xy is 64.

    Let's check our work against equation (1):
    6 + 4 ? 10
    10 = 10

    Let's check our work against equation (2):
    10(6)+ 4 ? 15(4) + 4
    60 + 4 ? 60 + 4
    64 = 64
     

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