The increase is 917 - 712 = 205.
205 is what percent of 712?
"is" means =
"what" means x
"percent" means /100
"of" means *
205 = x/100 * 712
205 = x * 7.12
x = 205 / 7.12
x = about 28.8
Answer: There was an (about) 28.8% increase in sales from last year (712) to this year (917).