If a retail jeweler sells a pair of gold earrings for $213.90. The jeweler uses a 130% markup based on cost.
Answers:
A. $93.00 C. $276.90
B. $164.53 D. $278.07

I did:
Change 130% to 1.3 factor

Cost x 1.3 = $213.90

So cost = 213.90/1.3 = $164.54
I s this correct?

The answer is (d) 278.07

213.90 * 1.3 = 278.07 which mean the saler will profit $64.17

The answer is (d) 278.07

213.90 * 1.3 = 278.07 which means the saler will profit $64.17

The original poster was correct. The 213.90 retail price is after the markup has already been applied, not before.

This can be checked. 164.54 is the cost. A 30% markup based on cost would then be 164.54 x .30 = 49.36. And cost of 164.54 plus markup of 49.36 = 213.90, the retail price and it checks out.