How many 3-digit numbers are there such that the sum of the hundreds digit and the tens digit is equal to the ones digit?

101 , 112 , 123 , 134 , 145 , 156 , 167 , 178 , 189 , 202 , 213 , 224 , 235 , 246 , 257 , 268 , 279 , 303 , 314 , 325 , 336 , 347 , 358 , 369 , 404 , 415 , 426 , 437 , 448 , 459 , 505 , 516 , 527 , 538 , 549 , 606 , 617 , 628 , 639 , 707 , 718 , 729 , 808 , 819 , 909 , Total =  45 such 3-digit numbers.