Jo started collecting stamps. So far he has 12 stamps. The number of U.S stamps,u, is 3 less than twice the number of foreign stamps,f. How

I assume you want to find the number of each type of stamp.

Let x be the number of US stamps and y be the number of foreign stamps

So we have

x + y = 12

And the statement....The number of U.S stamps is 3 less than twice the number of foreign stamps.....can be written as

x + 3 = 2y

So using the first equation, we can let  y = 12 - x....so...in the second equation, we have

x + 3  = 2(12 -x)   simplify

x + 3 = 24 - 2x     add 2x to both sides and subtract 3 from both sides

3x = 21     divide by 3 on both sides

x = 7    which implies that y = 5

So, he has 7 US stamps and 5 foreign stamps....

jo has 12 stamps, 3 U.S stamps and 9 foreign stamps.