A man is 4 times as old as his daughter,9 years ago the sum of their ages was 42 find their present ages .
m = 4 d
(m - 9) + (d - 9) = 42
substituting ... (4 d - 9) + (d - 9) = 42 ... 5 d - 18 = 42
solve for d , then substitute back to find m
(m - 9) + (d - 9) = 42
substituting ... (4 d - 9) + (d - 9) = 42 ... 5 d - 18 = 42
solve for d , then substitute back to find m