Answer:

Let x be the present age of his son.

Age of father  =  30 + x

One year ago,

Son's age  =  x - 1

Father's age  =  30 + x - 1

Father's age  =  29 + x

29 + x  =  4(x - 1)

29 + x  =  4x - 4

4x - x  =  29 + 4

3x  =  33

x  =  11

Father's present age  =  30 + 11

=  43

So, the father's present age is 43 years.

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Step-by-step explanation:

Answer: 41 years old

Since the problem hinted that he is four time older than his son one year ago, it must mean his age one year was an even number as well as his son's. If last year he was a year younger so must his son. So were looking for a reasonable age where the son's age could be multiplied with 4, resulting to the father's age. Since the father is 30 years older, he must be above 30 years old currently.

• Look for numbers above 30 which could be divided by 4

32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72 and so on

• Identify the son's possible age, since the father is 30 years older we must subtract 30 from these numbers

2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42

• Look for the relationship, find out which number if multiplied by 4 it's related to the numbers above it.

2 x 4 = 16

6 x 4 = 24

10 x 4 = 40

• I guess 40 is now the father's age last year, add 1 and you'll get the father's current age, 41