Mrs Lau baked some biscuits of three flavours, which were apple, cranberry and chocolate chip. She baked twice as many apple biscuits as cranberry biscuits and twice as many chocolate chip biscuits as apple biscuit. Given that she baked 90 more chocolate chip biscuits than cranberry biscuits, how many biscuits did she bake?
Number of cranberry biscuits = 1 u
Number of apple biscuits = 2 u
Number of chocolate chip biscuits = 2 x 2 u = 4 u

Number of more chocolate chip biscuits than cranberry biscuits
= 4 u - 1 u 
= 3 u

3 u = 90

1 u = 90 ÷ 3 = 30

Number of apple biscuits
= 2 u
= 2 x 30
= 60

Number of chocolate chip biscuits
= 4 u
= 4 x 30
= 120

Total number of biscuits that he baked
= 30 + 60 + 120
= 210

Answer(s): 210