Question

"the sum of two numbers is 80. if the larger number exceeds four times the smaller by 5, what is the smaller number"

Answer 1

Let x and y be the two numbers. And x > y.
Then,
x + y = 80
Also,
x = 4y - 5
Solving the two equations,
80 - y = 4y - 5
75 = 5y
Therefore, y = 15.
Hope this helps you.