Find the value of two numbers if their sum is 15 and their difference is 1.

Question

Find the value of two numbers if their sum is 15 and their difference is 1.

We need to find out what x and y represents and the system of equations.

Answer 1

let the two numbers be x and y

from the word problem:

their sum is 15 which means if you add them together you get 15

x + y =15

their difference is 1 which means subtract one from the other and you get 1 - it does not matter which variable you use for each here:

x - y = 1

x + y = 15

x - y = 1

Use substitution

x = 1 + y (isolate x so you can get rid of it in the 1st equation)

1 + y + y = 15 (substitute for x in 1st equation)

1 + 2y = 15

2 y = 14

y = 7

x + 7 = 15

x = 15 - 7 = 8

so x = 7, y = 8

Answer 2

Just thinking about it, I would say 7 and 8.

x + y = 15

x - y = 1

2x = 16

x = 8

y = 7