If the radius of the base of a cylinder increases by 4 cm, its lateral area increases by 125.6 cm2. If the circumference of its base increases by 3 cm, how much does its lateral area increase?
一个圆柱体底面半径增加4厘米，它的侧面积就增加125.6平方厘米，如果它的底面周长增加3厘米，它的侧面积增加多少？
<gadget id="calculator">2 * 4 * 3.14</gadget>
<output>25.12</output>

<gadget id="calculator">125.6 / 25.12</gadget>
<output>5</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>