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the ratio of sunita's age to mark's age is currently 3 to 4, and in 12 years, it will be 5 to 6. what is mark's current age?
a
18

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.

The answer is 225 miles per 4.5 hours. hope this ; )