Question

The sum of two numbers is 217. The difference between them is 43. Find the two numbers.

Answer 1

The numbers are 87 and 130

Explanation:

• Call the numbers x and y
• 
  `x+y=217` [1]
• 
  `y-x=43` [2]
• Rearrange [2] to make y the subject
• 
  `y=43+x` [3]
• Substitute [3] into [1]
• 
  `x+(43+x)=217`
• 
  `2x+43=217`
• 
  `2x=174`
• 
  `x=87` [4]
• Use [4] for [2]
• 
  `y-87=43`
• 
  `y=130`