Formulating an equation for this situation we have:
S = C + 0.2(C) (S: selling price, C: Cost , 0.2= 20%)
130 = C + 0.2C (Replacing)
130 = 1.2C (Adding like terms)
130/ (1.2) = C (Dividing on both sides by 1.2)
108.333=C (Dividing)
The answer is $108.33 (Rounding to the nearest cent)