This year, the age of the mother is five times that of the son; three years later, the age of the mother is four times that of the son, what is the sum of the ages of the mother and the son now?
今年母亲的年岁是儿子的5倍；3年后，母亲的年岁是儿子的4倍，求現在母子岁数的总和？
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">12 - 3</gadget>
<output>9</output>

<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">9 / 1</gadget>
<output>9</output>

<gadget id="calculator">9 * 5</gadget>
<output>45</output>

<gadget id="calculator">9 + 45</gadget>
<output>54</output>

<result>54</result>