Usha, Abir and Ratul are three brothers. Their father has divided Tk. 4200 amongst them. Thus Abir gets5 /3

parts of Usha and Usha gets1 /2
parts of Ratul.

a. If a : b = 4 : 5, b : c = 7 : 9, determine a : b : c.

b. Find the ratio of amount of Usha, Abir and Ratul.

c. Find How much taka Usha, Abir and Ratul have got?
(Pls i need this ans now)​

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.