Question

The sum of two numbers is 20. The difference between three times the first number and twice the second is 40. Find the two numbers.

Answer 1

Their sum can be written as : a+b=20. this means that b=20-a

and the phrase: The difference between three times the first number and twice the second is 40 like this:

3a-2b=40

and we can substitute:
3a-2b=40
 3a-2(20-a)=40
 3a-40+2a=40

5a=40+40
5a=80

a=16
so b must be 4!

let's check:

3*16-2*4=48-8=40 correct!