Answer:
Caroline will have to earn $45,000 to maintain her standard of living in city B
Explanation:
Cost of living index compared cost of living in different locations. It measures the prices of goods and services offered in a location over time.
For city A the index she earns $40,000 at 80 cost of living index
Therefore she will earn x at city B with 90 cost of living index.
Cross multiply
80x= 90*40,000
x= (90*40,000)/80
x = $45,000
Caroline will have to earn $45,000 to maintain her standard of living in city B