Eli is now one quarter of his father’s age. In 5 years’ time his age will be one third of his father’s age. How old is Eli now?

10

Step-by-step explanation:

This is because 10×4=40

10+5=15

40+5=45

45/15=3

Step-by-step explanation:

Let E and F represent Eli and his Father's current ages.

We are told that E = (1/4)F.  ["Eli is now one quarter of his father’s age"]

But in 5 years, that will be:

(E+5) = (1/3)(F+5)       ["In 5 years’ time his age will be one third of

his father’s age"]

We have two equations and two unknowns.  Find a way to eliminate one of the two variables and then solve for the remaining variable.

E = (1/4)F

(E+5) = (1/3)(F+5)

It seems to me the easiest would be to use the first equation's definition of E [=(1/4)F] in the second equation:

(E+5) = (1/3)(F+5)

((1/4)F+5) = (1/3)(F+5)

(1/4)F - (1/3)F = (1/3)*5 - 5

F - (4/3)F = (4/3)*5 - 20

-(1/3)F = (20/3) - (60/3)

-(1/3)F = (-40/3)

F = (120/3)

F = 40 years

E = 10 years  (based on E = (1/4)F)

In five years:  F is 45 and E is 15, which would make Eli  1/3 of his father's age in 5 years.

by definition, an arc subtended by a central angle of some given measure has the same measure. so .

throw the computer

step-by-step explanation: