Short answer: 375 grams
Remark
You only need to set up a direct proportion
Givens
flour for 12 cakes = 150 grams
Number of cakes initially = 12
Amount of flouer for 30 cakes = x
Number of cakes = 30
Proportion
amount flour for 12 cakes / 12 cakes = x / 30
Sub and solve
150 grams / 12 cakes = x / 30 cakes Cross multiply
150 * 30 = 12 *x Multiply the left side.
4500 = 12 x Divide both sides by 12
4500/12 = x
375 grams for 30 cakes. <<<<< Answer
