the sum of the present age of a father and his son is 40 years 4 years has father will be three times as old as his son will be find their present age​

Let’s define our variables:

D = dad’s age now

S = son’s age now

Given:

D=4S now

D+4=3(S+4) in 4 years

We can expand the second equation:

D+4=3S+12

D=3S+8

And we can subtract it from D=4S

D=4S-(D=3S+8)

0=S-8

S=8 the son’s age now.

D=4S=4(8)=32 the father’s age now

Check:

32+4=3(8+4)

36=3(12)

36=36 Check

I hope this helps you

percentage - 25%

probability - 0.25

we know,

total amount of students in class = 20

total boys = 10

total girls = 10

no of girls who wear glasses = 10/2 = 5

probability of choosing a girl with glasses is =

number of girls wearing glasses/total number of students in the class = 5/20

thus, percentage of selecting a girl wearing glasses will be

= 5/20 × 100

= 5 × 5

25%

therefore,

probability will be 0.25

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