Answer:
Rahim is 14 and his father is 42.
Explanation:
Let F be Rahim's father's age and R is Rahim's age.
We learn that:
F = 3R [Rahim's father's age is 3 times as old as him]
and
F + R = 56 [their sum is 56]
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We have 2 equations and two unknowns, so we should be able to find the answers.
Rearrange the second equation to: F = 56 - R
The use that definition of F in the first equation:
F = 3R
(56-R) = 3R
Then we can find R:
56-R = 3R
4R = 56
R = 14
Since R=14 and F + R = 56,
F + R = 56
F + 14 = 56
F = 42
Check
Does F=3R?
42 = 3(14)? YES
Does F + R = 56?
42 + 14 = 56? YES
Rahim is 14 and his father is 42.