To make salsa, Peter needs 8 oz of tomatoes for every 3 oz of other ingredients. To make spaghetti sauce, he needs 16 oz of tomatoes for every 5
oz of other ingredients. Peter has 48 oz of tomatoes.

we need to divide the number of toy dinosaurs, 156, by the number of brothers, 4:

in order to estimate, we can use compatible numbers:

156 ÷ 4

  ↓

160   ÷ 4 = 40        

the correct answer is a).

well if you have a decimal you have to line them up and make sure the you have everything   straight and then add or subtract some thing with   division and   multiplying so just like them up