Question

The sum of the present age of a mother and her son is 35 and the difference is 25 years.find their present age.(By substitution or elimination method).​

Answer 1

Answer:

Son = 5 years old

Mum = 30 years old

Step-by-step explanation:

Let the Mum be M and the Son be S;

$M + S = 35$ --- Sum

$M - S = 25$ -- Difference

Required

Find M and S (their ages)

Using elimination method; Add both equations to eliminate S

$M + S = 35$

$M - S = 25$

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$M + M + S - S = 35 + 25$

$2M = 60$

Solve for M

$M = \frac{1}{2} * 60$

$M = 30$

Substitute 30 for M in $M + S = 35$

$30 + S= 35$

Solve for M

$S = 35 - 30$

$S = 5$

Hence:

Son = 5 years old

Mum = 30 years old