Fractional equations

Question

Two numbers are in the ratio 7:3. One third of their sum is 30. Find the numbers using fractional equations 

Answer 1

ratio is 7:3

7x and 3x are the numbers

(7x+3x)/3=30

(7x+3x)=30*3

10x=90

x=90/10

x=9

7x=7*9=63

3x=3*9=27

63+27=90, (1/3)(90)=30, and 63/27=21/9=7/3