Question

the sum of two number is 18.if their sum is four time their difference find the number

Answer 1

let two numbers be x and y,(x>y)
x+y=18.........................(1)
now,
x+y=4(x-y)
x+y=4x-4y
5y=3x
or,y=3x/5......................(2)
put the value of y from eq(2) into eq(1)
x+3x/5=18
8x/5=18
x=45/4
y=27/4

Answer 2

Answer:

x=45/4 y=27/4

Step-by-step explanation:

x+y=18               .....(i)

x+y=4(x-y)

x+y=4x-4y

4y+y=4x-x

5y=3x

3x-5y=0            .....(ii)

By elimination method

(x+y=18)3

3x-5y=0

3x+3y=54

3x-5y=0

8y=54

y=54/8=27/4

By substituting for y in equation (i) we get

x+27/4=18

x=18-27/4

x=45/4

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