Answer:
140
Explanation:
To find the least common multiple, you list the multiples of each number, then, identify the SMALLEST number they have in COMMON.
28: 28, 56, 84, 112, 140, 168, 196, 224, 252, 280, 308, 336
10: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150
The smallest number that 28 and 10 have in common is 140.