Math prodigy yay

Question

I’m confused when they ask me on Prodigy to have a sum of two numbers that equal for example 16 and if you subtract those two numbers that equal 16 to get four I’m confused

Answer 1

Or, you can add the two equations.

x + y = 16

x - y = 4

2x = 20

x = 10

10 + y = 16

y = 6

Answer 2

The idea is to figure out what the two numbers are. Since we don't know yet, we'll start by calling them x and y. We know their sum equals 16:

x + y = 16

We know their difference equals 4:

x - y = 4

Add y to both sides of this equation and you get:

x = y + 4

Substitute y + 4 in place of x in the first equation:

x + y = 16

y+4 + y = 16

2y + 4 = 16

2y = 12

y = 6

x = y+4

x = 6 + 4

x = 10

The two numbers are 6 and 10. Is their sum 16? 10 + 6 = 16. Yes! Is there difference 4? 10 - 6 = 4. Yes!