We have to determine the number of blocks. We know that that number have 9 in the ones place. It also has the number in the hudreds place ( x ) which is 1 more than the number in the tens place ( y ). And: x + y = 11. Another equation is: x = y + 1. Therefore y + 1 + y = 11; 2 y = 11 - 1; 2 y = 10; y = 10 : 2; y = 5 and x = 5 + 1 = 6. Answer: There are 659 blocks.
