x=2/5y, x+y=21

Question

The sum of two numbers is 21. The first number is 2/5 of the second number. What are the numbers?

Answer 1

me assume that stuf shood be

1... x=(2/5)y

2...x+y=21...x=21-y

(2/5)y=21-y...2y=105-5y

2y+5y=105...7y=105

y=15

x=21-y...x=21-15...x=6

Answer 2

Let the number are x and y

Then,
x=2/5y...(1)
x+y=21...(2)

Substitute x value in equation (2) from equation (1)
2/5y+y=21
y=15

Substitute y value in equation (1)
x=2/5*15
x=6

Free College Algebra Help - http://math.tutorvista.com/algebra.html