Question 1163711
The sum of Sofia's age and Sonya's age is 65. Eleven years ago, Sonya was seven less than four times as old as Sofia. Find Sofia's age now.
<pre>Let Sofia's age be S
Then Sonya's is: 65 - S
We then get: 65 - S - 11 = 4(S - 11) - 7
54 - S = 4S - 44 - 7
- S - 4S = - 44 - 7 - 54
- 5S = - 105
Sofia, or {{{highlight_green(matrix(1,6, S, "=", (- 105)/(- 5), "=", 21, years-old))}}}