determing cell x and y of a canvas grid

I have a nodejs application that creates a grid within a canvas currently using for loops. I need help writing an algorithm to determine which cell i my cursor is currently in x and y wise. The grid is currently 25x25 and I am tracking mouse movements within the canvas. Instead of giving me a raw x and y mouse coordinate I would like a cell coordinates. any help? thanks!

//START {EXPRESS}
var express = require('express');
var app = express();
var serv = require('http').Server(app);
 
app.get('/',function(req, res) {
    res.sendFile(__dirname + '/client/index.html');
});
app.use('/client',express.static(__dirname + '/client'));
 
serv.listen(2000);
console.log("Server started.");


var io = require('socket.io')(serv,{});
io.sockets.on('connection', function(socket){
        //RETRIEVING THE MOUSE X AND Y COORDINATES
        socket.on('mouseMove', function(data){
                console.log(data.x + ", " + data.y);
        });

});

<div id="gameDiv">
        <center>
        <canvas id="ctx" width="750" height="750" style="border:1px solid #000000;"></canvas>
        </center>
</div>
        
<script src="https://cdn.socket.io/socket.io-1.4.5.js"></script>
        
<script>
        //NETWORK VARIABLES
        var socket = io();
        //GETTING THE CANVAS BY ID
        var canvas = document.getElementById("ctx");
        context = canvas.getContext("2d");
        
        //GRID VARIABLES
        var w=30,
        h=30,
        row=25,
        col=25,
        x=0,
        y=0;
        
        //LOOP TO DRAW THE GRID
        for(x=0; x<row; x++){
                for(y=0; y<col; y++){
                        context.strokeRect(w*x,h*y,w,h);
                }
        }
        
        //GETTING THE MOUSE X AND Y
        function getMousePos(canvas, event){
                var rect = canvas.getBoundingClientRect();
                return {
                        x:event.clientX - rect.left,
                        y:event.clientY - rect.top
                };
        }
        
        canvas.addEventListener('mousemove', function(event){
                var pos = getMousePos(canvas, event);
                var posx = pos.x;
                var posy = pos.y;
                
        socket.emit('mouseMove',{x:x, y:y});
        }, false);
        
        
        
</script>

</html>

via Jaekx