Tyson has a collection of 60 sports ribbon 30% are first place ribbons 45% are second place ribbons and the rest are third place ribbons are in tysons sport ribbon collection

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.

i belive those are the ones that are under 90 degreese.