Question 1206436
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At present Mary is 6 times as old as her daughter Susan. Four years from now she will be only four times as old as Susan. What is the sum of their ages at present?

Let Susan's age be S
Then mother's (Mary's) age is 6S
Sum of their ages: S + 6S = 7S

Four (4) years from now, Mary will be 6S + 4, and Susan will be S + 4
      We then get: 6S + 4 = 4(S + 4)
                   6S + 4 = 4S + 16
                  6S - 4S = 16 - 4
                       2S = 12
       Susan's age, or {{{matrix(1,5, S, "=", 12/2, "=", 6)}}}
<font color = red><font size = 4><b>Sum of their ages:</font></font> 7S = 7(6) = <font color = red><font size = 4><b>42</font></font></b></pre>