As given, the current height of Bobby is = 61 inches
Bobby hopes to be taller than 70 inches.
Let the number of inches Bobby needs to grow to reach 70 be = x
So, he needs to grow
[tex]x+61=70[/tex]
Hence, x=9 inches
So, Bobby needs to grow 9 inches to reach a height of 70 inches and more than 9 if he wants to be taller than 70 inches.