Kevin is 3 years older than Daniel. Two years ago, Kevin was 4 times as old as Daniel.
Let k be Kevin's age and let d be Daniel's age.

Answer  :  Define F as fathers age and S as sons age right now.

Then now they are

(1) 3S = F

and six years ago they were

(2) 5*(S-6) = F-6

calculate 5*(S-6)

5S - 30 = F-6

Subtract left and right side by -F

Add 30 to left and right side

5S - F = 24

Put (2) 3S = F into the equation above

5S - 3S = 24

2S = 24

S = 12

insert result in (2) 3S = F

3*12 = F

36 = F

So the son is 12 years, and the father is 36 years.

b) 1/3 * 1/5

step-by-step explanation:

each smallest part is 1/15 since the written one is 1/5 and it's divided by 3 equal parts. (1/5 )/3 = 1/15 = 1/3 * 1/5