Question

One number is fifteen less than 4 times another. If the sum of the two numbers is
twenty, find the two number.

Answer 1

Given :-

• One number = 15 less than 4 times other
• Sum of two numbers = 20

To Find :-

• Both numbers

Solution :-

Let one number be'x' and another number be'y'

then ,

According to question :-

• One number = 15 less than 4 times another
• x = 4y - 15. --(1)

Now,

• Sum of two numbers = 20

➮ x + y = 20

➮ x = 20 - y --(2)

From (1) and (2) , we get,

➮ 20 - y = 4y - 15

➮ 20 + 15 = 4y + y

➮ 5y = 35

➮ y = 35/5

➮ y = 7

Put y = 5 in (1) , we get,

➮ x = 4y - 15

➮ x = 4(7) - 15

➮ x = 28 - 15

➮ x = 13

Hence,

• One number is x = 13
• Another number is y = 7

Answer 2

Answer:

Given :-

• One number is fifteen less than 4 times other
• Sum = 20

To Find :-

Numbers

Solution :-

Let the number be x

$\sf \: x + \bigg \lgroup4x - 15 \bigg\rgroup = 20$

$\sf \: x + 4x - 15 = 20$

$\sf \: 5x + 15 = 20$

$\sf \: 5x = 20 + 15$

$\sf \: 5x = 35$

$\sf \: x \: = \dfrac{35}{5}$

$\sf \: x \: = 7$

Numbers are

x = 7

4x - 15 = 4(7) - 15 = 28 - 15 = 13

Verification :-

x + 4x - 15 = 20

7 + 4(7) - 15 = 20

7 + 28 - 15 = 20

35 - 15 = 20

20 = 20

Hence verified.