Sam uses 140g of flour to make 12 cakes. How much flour will Sam need to make 21 cakes?

This question can be difficult, because it involve a lot of words. This can make it confusing as to what information we really need to use - just work it through step by step.

Sam uses 140g of flour to make 12 cakes. In order to answer this question we need to find out how much flour is used to make 1 cake.

To do this we divide 140 by 12:

140 / 12 = 11 2/3

Next, we must find out how much flour is needed to make 21 cakes.

To do this, we mutiply the number of flour needed to make 1 cake by 21:

11 2/3 x 21 = 244.9999

Because it would be difficult to measure 244.9999g of flour, we simply round up to the nearest whole number:

= 245g of flour is needed to make 21 cakes.