main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

double kHeight = 100;
double kWidth = 100;

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: SafeArea(
          child: Card(
            child: Wrap(
             alignment: WrapAlignment.end,
              children: [
                Row(mainAxisSize: MainAxisSize.min, children: [
                  Container(child: Text("A"), height: kHeight, width: kWidth),
                  Container(child: Text("B"), height: kHeight, width: kWidth),
                  Container(child: Text("C"), height: kHeight, width: kWidth),
                ]),
                Wrap(
                  children: [
                    Container(
                        child: Text("1"),
                        height: kHeight / 2,
                        width: kWidth / 2),
                    Container(
                        child: Text("2"),
                        height: kHeight / 2,
                        width: kWidth / 2),
                    Container(
                        child: Text("3"),
                        height: kHeight / 2,
                        width: kWidth / 2),
                  Container(
                      child: Text("4"), height: kHeight / 2, width: kWidth / 2),
                  Container(
                      child: Text("5"), height: kHeight / 2, width: kWidth / 2),
                  Container(
                      child: Text("7"), height: kHeight / 2, width: kWidth / 2),
                ])
              ],
            ),
          ),
        ),
      ),
    );
  }
}