Answer:
One number is 4, the other is 11
Step-by-step explanation:
"The sum of two numbers is 15" can be written as
x + y = 15 where x is one number, and y is the other. Their sum is 15
"one number is 7 less then the other' can be written as
x = y - 7 x is one number that is 7 less than the other
Now we know x = y - 7. We can plug that into the first equation x + y = 15 and solve...
The first equation is now...
y - 7 + y = 15 ('x' is substituted for y - 7)
Now solve...
2y - 7 = 15 (combine like terms)
2y = 22 (add 7 to both sides to isolate the term with the variable)
y = 11 (divide both sides by 2 to isolate the variable)
If y = 11, then
x + 11 = 15 (the 'y' in the first equation becomes 11)
Then x = 4 (subtract 11 from both sides to isolate x)
