Two cylindrical containers, A and B, have a bottom area ratio of 4:3, the water depth of A container is 7 cm, and the water depth of B container is 3 cm. Then pour the same amount of water into each of the two containers until the water depth is equal. How many centimeters is the water depth at this time?
甲、乙两个圆柱形容器，底面积比为4：3，甲容器水深7厘米，乙容器水深3厘米．再往两个容器各注入同样多的水，直到水深相等，这时水深几厘米？
<gadget id="calculator">7 - 3</gadget>
<output>4</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

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

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">12 + 7</gadget>
<output>19</output>

<result>19</result>