The sum of two numbers is 30 and their difference is 20. What are the two numbers?
3 Answers
5 and 25
Explanation:
Explanation:
Two numbers, x and y, have this relationship:
We can solve this - it's 2 equations with 2 unknowns. I'll take the second equation, solve for x, then substitute into the first one:
And so
We can now substitute this back into either starting equation - I'll do both to show that it works in both:
It all checks!
one number is
Explanation:
The problem asks for the identity of two unknown numbers.
This makes the problem one with two variables.
With two variables it is necessary to have two equations.
Let x be one number
Let y be the other number.
Solving the second equation for x
Substituting this value into the first equation gives.
#2y = 10# Dividing both sides by #2# to isolate #y# results in
The two unknown numbers are