At 6:00 A.M. the temperature was 33°F. By noon the temperature had increased by 10°F and by 3:00 P.M. it had increased another 1
2°F. If at 10:00 P.M. the temperature had decreased by 15°F, how much does the temperature need to rise or fall to return to the original temperature of 33°F?
500 in 2:3 is saying that there are five different parts (2 + 3) This means that 500 needs to be split into five, which is 100. After that all you need to do is put 2 'sections' on one side and 3 on the other.
For example, 2 : 3 = 2( x 100) : 3( x 100) = 200 : 300
