So, let us call our numbers a and b.
Statement 1:
a is thrice to b or: a = 3*b
Statememt 2:
Their (a’s and b’s) sum is 80: a+b =80
Together we have the two linear equations:
a=3b
a+b=80
Solving them can be done by using the fact that a is equal to 3b and plugging this into the second equation:
3b + b = 80
Now 3 apples plus 1 apple is 4 apples, right? So 3b + b = 4b !
4b = 80
No we divide by 4 and get the result for b:
b = 20
Now how do we find a? Well we know that a = 3b. So we just plug the solution for b into this equation:
a = 3 * 20 = 60.
That means the two numbers were 20 and 60