Mary’s annual income is $15,000 and John’s annual income is $18,000. By how much must Mary’s annual income increase so that it constitutes 80% of Mary and John’s combined income? Select:
A) $3,000
B) $4,000
C) $7,000
D) $11,000
E) $57,000
Let Mary's income increase by x, then the equation will be   15,000 + x= (80/100)* (15,000 + x + 18000 )   15,000 + x = (4/5) * (33,000 + x)   75,000 + 5x = 4x + 132,000   x = 57,000   x = 57,000   So, Answer will be $57,000
<result>E</result>
Mary’s annual income is $15,000 and John’s annual income is $18,000. By how much must Mary’s annual income increase so that it constitutes 80% of Mary and John’s combined income?