the ratio of toddlers to infants at a day care center is 7 to 3 . if 12 more infants join the day care to change the ratio to 7 to 5 , how many toddlers are there at this day care center ? Choose the most appropriate option.
A) 24  B) 36  C) 42  D) 72  E) 120

Rationale: 5 x - 3 x = 12 so , 2 x = 6 hence no of toddlers is 6 * 7 = 42 answer will be ( c ) 42
Answer: C