Answer:
Their present age are 15 and 18
Step-by-step explanation:
a : b = 5 : 6
[tex]\frac{a}{b} = \frac{5}{6} \\\\6a = 5b\\\\a = \frac{5b}{6} \\\\\frac{a-3}{b-3} = \frac{4}{5} \\\\5(a-3) = 4(b-3)\\\\5a - 15= 4b - 12\\\\5a - 4b = 15 - 12\\\\5a - 4b = 3\\\\substitute \ the \ value \ of \ a \ into \ the \ above \ equation;\\\\5(\frac{5b}{6} ) - 4b = 3\\\\25b - 24b = 18\\\\b = 18\\\\now, \ solve \ for \ a;\\\\a = \frac{5}{6} \times 18\\\\a = 15[/tex]
