Divide 100 ml into the ratio 3:7

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

Convert the mixed numbers into improper fractions. convert the improper fraction to mixed numbers.