Here is one possible solution using JavaScript:
function findGreatest(a, b, c) {
let greatest = a;
if (b > greatest) {
greatest = b;
}
if (c > greatest) {
greatest = c;
}
return greatest;
}
You can use this function by passing in any three numbers, like this:
let num1 = 5;
let num2 = 10;
let num3 = 7;
let greatest = findGreatest(num1, num2, num3);
console.log(greatest); // This will print 10 to the console
This code will find the greatest number among the three numbers a, b, and c by first setting the initial value of greatest to the value of a. It then checks if b is greater than greatest and updates the value of greatest if that is the case. Finally, it checks if c is greater than greatest and updates the value again if necessary. The function then returns the value of greatest, which is the largest of the three numbers