This example combines bars and a line chart to compare two related variables across a time series. It visualizes humidity as light blue bars on the left y-axis and temperature as a red line on the right y-axis, with a legend, gridlines, and axis labels for each scale. The chart renders synthetic sine-wave data in an SVG using d3.scaleLinear for both axes, d3.axisBottom, d3.axisLeft, and d3.axisRight for ticks, and d3.line for the temperature path. A React version loads student performance data via d3.tsv, groups records into intervals, and plots average study time as bars against average absences as a line.