Once because 7 - 49 = -42 but you can subtract 7 from 49 seven times
From the first term subtract 19 to get the second, and continue to subtract the next smaller odd number to proceed down the line:100 (-19) 81 (-17) 64 (-15) 49 (-13) 36 (-11) 25 (-9) 16
68
21
9
Subtract a negative 1. 19 - (-1) = 20
30 + 19 = 49
49 x 19 = 931
19
"negative 49 over 19" is the ratio of -49 to 19. That's rational.
solve in reverse 49+15=64 64/8=8 8 is the answer 8*8-15=49
7 can be subtracted from 49 only one time.