36: 6 <-- explanation of square root: any number that when multiplied by itself equals your wanted number (in this case 36) will be the square root of your wanted number.
Since they are FEWER than 30 total cones, the sum of x small cones and y large one must be LESS THAN 30: x+y <30 He needs AT LEAST a dozen (12), so that means that 12 will work or more than 12:
