Answer:
20 + 10 = 30
Explanation:
The sum of x and y is 30. In other words, x plus y equals 30 and can be written as equation A:
x + y = 30
The difference between x and y is 10. In other words, x minus y equals 10 and can be written as equation B:
x - y = 10
Now solve equation B for x to get the revised equation B:
x - y = 10
x = 10 + y
Then substitute x in equation A from the revised equation B and then solve for y:
x + y = 30
10 + y + y = 30
10 + 2y = 30
2y = 20
y = 10
Now we know y is 10. Which means that we can substitute y for 10 in equation A and solve for x:
x + y = 30
x + 10 = 30
X = 20
Summary: The sum of two numbers is 30 and their difference is 10. What are the two numbers? Answer: 20 and 10 as proven here:
Sum: 20 + 10 = 30
Difference: 20 - 10 = 10