Answer:
78.21
Step-by-step explanation:
so lets call this mystery number x and make an equation
x - 9.3 = 68.91
if you add 9.3 to both sides you'll find your answer because you are isolating r by getting rid of the 9.3
and you add it to the 68.91 because if you do something to one side of the equation, then you must do it to the other
68.91 + 9.3 = 78.21
that means 78.21 = x
to ensure that this is your answer, there is a 7 in the tens place, a 2 in the tenths place, and a 1 in the hundredths place