Xiaohong conducted a survey and statistics on the way students in lower grades went to school. There were 135 students who were picked up by their parents, accounting for 90% of the total number of people surveyed. How many people did Xiao Hong investigate?
小泓对低年级同学的上学方式进行了调查统计，通过家长接送的有135人，占总调查人数的90%．小泓调查了多少人？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">135 / (9/10)</gadget>
<output>150</output>

<result>150</result>