How to promote Qgraphicsview in Qchartview?

I'm new to Qt Creator, I want to know how to display 2 or 3 graphics on a single screen, I've already seen some examples that Qt provides, but they do not show how I want to learn how to do it, please Help. p>

/file.cpp

#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtCharts/QChartView>
#include <QtCharts/QPieSeries>
#include <QtCharts/QPieSlice>

QT_CHARTS_USE_NAMESPACE

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

QPieSeries *series = new QPieSeries();
series->append("", 1);
series->append("", 2);
series->append("", 3);
series->append("", 4);
series->append("", 5);

QChart *chart = new QChart();
chart->addSeries(series);
chart->setTitle("Example");
chart->legend()->show();

QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::Antialiasing);

QMainWindow window;
window.setCentralWidget(chartView);
window.resize(400, 300);
window.show();

return a.exec();
}

BarChart.cpp

#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtCharts/QChartView>
#include <QtCharts/QBarSeries>
#include <QtCharts/QBarSet>
#include <QtCharts/QLegend>
#include <QtCharts/QBarCategoryAxis>
#include <QtCharts/QValueAxis>

QT_CHARTS_USE_NAMESPACE

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QBarSet *set0 = new QBarSet("Jane");
    QBarSet *set1 = new QBarSet("John");
    QBarSet *set2 = new QBarSet("Axel");
    QBarSet *set3 = new QBarSet("Mary");
    QBarSet *set4 = new QBarSet("Samantha");

    *set0 << 1 << 2 << 3 << 4 << 5 << 6;
    *set1 << 5 << 0 << 0 << 4 << 0 << 7;
    *set2 << 3 << 5 << 8 << 13 << 8 << 5;
    *set3 << 5 << 6 << 7 << 3 << 4 << 5;
    *set4 << 9 << 7 << 5 << 3 << 1 << 2;

    QBarSeries *series = new QBarSeries();
    series->append(set0);
    series->append(set1);
    series->append(set2);
    series->append(set3);
    series->append(set4);


    QChart *chart = new QChart();
    chart->addSeries(series);
    chart->setTitle("Simple barchart example");
    chart->setAnimationOptions(QChart::SeriesAnimations);

    QStringList categories;
    categories << "Jan" << "Feb" << "Mar" << "Apr" << "May" << "Jun";
    QBarCategoryAxis *axisX = new QBarCategoryAxis();
    axisX->append(categories);
    chart->addAxis(axisX, Qt::AlignBottom);
    series->attachAxis(axisX);

    QValueAxis *axisY = new QValueAxis();
    axisY->setRange(0,15);
    chart->addAxis(axisY, Qt::AlignLeft);
    series->attachAxis(axisY);

    chart->legend()->setVisible(true);
    chart->legend()->setAlignment(Qt::AlignBottom);

    QChartView *chartView = new QChartView(chart);
    chartView->setRenderHint(QPainter::Antialiasing);

    QMainWindow window;
    window.setCentralWidget(chartView);
    window.resize(420, 300);
    window.show();

    return a.exec();
}