Figure out how many degrees the temperature changed from midnight to noon.
-12 to 28 is 40.
So the temperature change was 40 degrees F from midnight to noon
Take -5x + 3x = -2x
because there is a -3x and a 3x they cancel each other out.
and the -17 is left
-2x = -17
divide -2 by -17 = 8.5
3:5=x:50
Therefore 5 ×x = 50
x = 10
Therefore 3 × 10 = 30
therefore 30 blue pens
proof = 30 blue + 50 red= 3+ 5
therefore 80 = 8x
