7.) (x, y) —> (1/2*x, 1/2*y)
15-9= 6 the difference is 6 people. i hope this is what you were looking for.
Multiply (13.2 cm) by (1 inch/2.54 cm). That gives you the whole length in inches. If it's more than 12, then take as many 12s away from it as you can, and call each of those '1 foot'. When you can't take 12 away any more, then what you have left is the inches.
Standard form is just putting (in this case) variables in alphabetical order. First we simplify- 2x+4=4y would become 1/2x+1=y. This is already in standard form, as numbers w/o variables come at the end. simplifying the next one is more tricky. first you get a variable/number alone-
9-2x-2y=4x+3
9-2y=6x+3
6-2y=6x
1-1/3y=x
1=x+1/3y
3=x+y
x+y=3
sorry if I was wrong and not of any help, But I do believe this is correct.
