First, turn the fractions into mixed numbers.
21/4 - 27/8
Then. make the denominators the same.
4 * 2 = 8
21 * 2 = 42
42/8 - 27/8
42 - 27 = 15
15/8
15/8 = 1 7/8
Answer:
the 1st one i think cause its 500 all together
1950 2,771,305
1960 4,951,560
1970 6,789,443
1980 9,746,324
1990 12,937,926
2000 15,982,378
2010 18,801,310
Sorry I couldn't find models.